Tl^- 


UNlVERSllY  0^^  CALIFORNIA, 

LIBRARY, 

a_OS  ANGELES,  CALIF. 


EDUCATIONAL    PSYCHOLOGY 


SECOND  EDITION 

REVISED  AND  ENLARGED 


BY 

EDWARD  L.  THORNDIKE 

PROFESSOR   OF   EDUCATIONAL  PSYCHOLOGY    IN    TEACHERS    COLLEGE 
COLUMBIA   UNIVERSITY 


-z  /  7  :2. 4- 


PUBLISHED   BY 

®?arlj^r0  (EalU^t,  Qlnlumhia  Unitrfraitg 

NEW  YORK 
1910 


2738 


'  i  ik: 


Copyright,   1903,   1910 
By  EDWARD  L.  THORNDIKE 


e94>s? 


PRESS    OF 

FRANK    H.    EVORY    &    CO 

ALBANY,    N.    Y. 


PREFACE 


This  book  is  a  revision  of  a  book.  Educational  Psychology, 
which  appeared  in  1903.  Its  primary  purpose  is,  as  was  the  case 
with  the  first  edition,  to  provide  students  in  advanced  courses  in 
educational  psychology  with  material  which  they  would  otherwise 
have  to  get  from  lectures  at  great  cost  of  time. 

The  chapter  on  '  The  Influence  of  Special  Training  upon  More 
General  Abilities  '  is  not  included  in  this  edition.  It  was  out  of 
place  before  since  it  treated  facts  of  mental  action  in  general 
instead  of  facts  of  individual  mental  conditions  and  their  causes. 
It  was  put  in  the  original  book  because  of  the  great  practical 
importance  of  the  facts  concerned.  The  facts  are  now  widely 
known  and  are  presented  conveniently  elsewhere. 

This  book  attempts  to  apply  to  a  number  of  educational 
problems  the  methods  of  exact  science.  The  problems  chosen  are 
those  of  the  mental  natures  of  individual  men,  and  the  causes  of 
their  differences.  The  problems  concerned  with  the  nature  of 
man  as  a  species, — the  general  problems  of  instinct,  habit, 
learning,  practice,  memory,  fatigue  and  the  like, — will  sometime 
be  treated  in  a  separate  volume.  The  two  together  will,  I  hope, 
be  a  serviceable  quantitative  treatment  of  educational  psychology. 


CONTENTS 


I 

3 
i8 

51 

69 

104 

114 


CHAPTER  PAGE 

I.     Introduction        ...... 

II.     The  Measurement  of  Individual  Differences    . 

III.  The  Influence  of  Sex    ..... 

IV.  The  Influence  of  Remote  Ancestry  or  Race 
V.     The  Influence  of  Immediate  Ancestry  or  Family 

VI.     The  Influence  of  Maturity    .... 

VII. y  The  Influence  of  the  Environment 

VIII.     The   Nature   and   Amount   of    Individual   Differences  in   Single 

Traits  .  .    *      .  .        142 

IX.     The  Relations  between  the  Amounts  of  Different  Traits  in  the 

Same  Individual    .  .  .  .  .171 

X.     The  Nature  and  Amount  of  Individual  Differences  in  Com- 
binations of  Traits;    Types  of  Intellect  and  Character     .        193 

XI.     Extreme  Individual  Differences;  Exceptional  Children    .  .       207 

APPENDIX 

I.     List  of  authors  and  titles  referred  to  specifically  in  the  text      .        231 

II.     List  and  descriptions  of  measurements  referred   to  cursorily 

in  the  text  .........       236 

III.     List  and  definitions  of  statistical  terms  used  in  the  text  .        242 


CHAPTER  I 

,  2-/724 
Introduction 

The  knowledge  of  human  nature  which  psychology  offers  to 
students  of  educational  theory  and  practice  may  be  roughly 
divided  into  four  parts.  A  body  of  general  knowledge  about 
instincts,  habits,  memory,  attention,  interests,  reasoning,  etc.,  finds 
place  in  the  ordinary  text-books.  Detailed  descriptions  of  the 
thoughts,  feelings  and  conduct  of  certain  children  at  different 
ages  are  available  in  the  literature  of  child  study.  Particular 
facts  which  bear  upon  this  or  that  school  subject  or  method  of 
teaching  may  be  gleaned  from  researches  upon  perception, 
association,  practice,  fatigue  and  other  topics.  Finally  there  is 
an  even  more  incoherent  mass  of  facts  about  the  differences 
between  one  human  being  and  another  and  the  respective  shares 
which  sex,  age,  '  race '  or  remote  ancestry,  '  family  '  or  immediate 
ancestry,  and  the  circumstances  of  life  have  in  the  causation  of 
these  differences.  It  is  the  aim  of  this  volume  to  put  this  last 
group  of  facts  at  the  service  of  students. 

Their  significance  for  educational  theory  and  practice  is  obvious. 
What  we  think  and  what  we  do  about  education  is  certainly 
influenced  by  our  opinions  about  such  matters  as  individual  differ- 
ences in  children,  inborn  traits,  heredity,  sex  differences,  the 
specialization  of  mental  abilities,  their  interrelations,  the  relation 
between  them  and  physical  endowments,  normal  mental  growth, 
its  periodicities,  and  the  method  of  action  and  relative  importance 
of  various  environmental  influences.  For  instance,  schemes  for 
individual  instruction  and  for  different  rates  of  promotion  are 
undertaken  largely  because  of  certain  beliefs  concerning  the 
prevalence  and  amount  of  differences  in  mental  capacity ;  the  con- 
duct of  at  least  two  classes  out  of  every  three  is  determined  in 
great  measure  by  the  teachers'  faith  that  mental  abilities  are  so 
little  specialized  that  improvement  in  any  one  of  them  will  help 

(1) 


2  Educational  Psychology 

all  the  rest ;  manual  training  is  often  introduced  into  schools  on 
the  strength  of  somebody's  confidence  that  skill  in  movement  is 
intimately  connected  with  efficiency  in  thinking;  the  practical 
action  with  regard  to  coeducation  has  been  accompanied,  and 
doubtless  influenced,  by  arguments  about  the  identity  or  the 
equality  of  the  minds  of  men  and  women ;  the  American  public 
school  system  rests  on  a  total  disregard  of  hereditary  mental  diflfer- 
ences  between  the  classes  and  the  masses ;  curricula  are  planned 
with  some  speculation  concerning  mental  development  as  a  guide. 
It  is  thus  easy  to  find  cases  where  educational  practice  depends 
upon  opinions  about  our  group  of  topics.  It  is  still  easier  to  note 
a  similar  dependence  in  the  case  of  educational  theory.  Abundant 
illustrations  will  appear  in  the  course  of  our  study  of  the  topics 
themselves. 

Effective  description  of  the  facts  of  individual  differences  and 
of  their  causation  must  be  quantitative.  The  questions  are 
questions  of  amount,  or  at  least  become  such  when  carried  beyond 
a  first  survey.  "Do  boys  and  girls  differ?"  is  itself  a  question 
of  amount,  which  soon  becomes,  "  How  much  do  boys  and  girls 
differ?"  "In  what  do  they  differ?"  can  be  answered  only  by 
comparing  them  quantitatively.  "Are  there  distinct  types  of 
children  with  respect  to  imagination?"  can  be  properly  answered 
only  by  measuring  children  in  respect  to  the  various  sorts  of 
imaginativeness  or  imagery  in  question.  "  What  is  the  value  of 
the  study  of  Latin?"  means  to  even  the  student  most  averse  to 
quantitative  thinking,  "What  changes  in  human  nature  are  caused 
by  it?"  But  to  prove  the  existence  of  any  change  one  must 
measure  two  conditions. 

It  is  therefore  necessary  to  understand  certain  elementary  facts 
about  the  means  and  methods  of  measuring  the  facts  of  individual 
differences  and  their  causation,  in  order  to  understand  the  facts 
themselves.  Portions  of  certain  chapters  will  consequently  be 
given  up  to  the  essentials  of  the  theory  and  practice  of  measuring 
mental  conditions,  differences,  changes  and  relationships. 


CHAPTER  II 

The  Measurement  of  Individual  Differences 

Exact  knowledge  of  the  nature  and  amount  of  individual  differ- 
ences in  intellect,  character  and  behavior  is  valuable  to  educational 
theory  and  practice  for  two  reasons.  The  first  is  the  general  need 
of  knowledge  of  what  human  beings  are  in  order  to  choose  the 
best  means  of  changing  them  for  the  better — a  need  which  includes 
knowledge  of  the  divergences  of  individuals  from  the  type  of  the 
species  as  a  whole,  as  well  as  knowledge  of  that  type.  Education 
needs  knowledge  of  men  as  well  as  of  man.  The  second  reason  is 
that  by  a  study  of  the  causes  of  these  differences, — the  causes 
^^hich  make  men  good  and  bad,  wise  and  foolish,  skillful  and 
clumsy,  efficient  and  futile, — education  may  hope  to  learn  about 
means  of  making  all  men  more  wise,  skillful  and  efficient.  The 
causes  of  the  dift'erences  betw-een  one  man  and  another,  as  things 
now  are,  will  lead  to  knowledge  of  the  causes  whereby  all  men 
may  be  made  to  differ  from  their  former  selves.  It  is  of  special 
importance  to  know  what  differences  amongst  men  are  due  to  dif- 
ferences in  sex,  race,  immediate  ancestry  and  maturity,  which  are 
beyond  control  by  ordinary  educational  endeavors,  and  what 
differences,  on  the  other  hand,  are  due  to  training  or  education 
itself. 

Simple  and  Compound  Differences 

A  difference  in  human  nature  may  be  (i)  in  the  amount  or 
degree  of  the  same  thing*  (as  'good — better,'  'quick — slow,' 
'  imaginative — less  imaginative — unimaginative  ')  ;  or  (2)  in  the 
presence  or  absence  of  different  things  (as  'John  knows  Latin; 
James  knows  German,'  or,  '  A  is  imaginative ;  B  is  rational,'  or, 
'  C  has  an  artistic  temperament;  D  has  a  scientific  temperament'). 

*0r  what  is  assumed  to  be  the  same  thing. 

(3) 


4  Educational  Psychology 

The  second  case  commonly  reduces  to  an  aggregate  of 
differences  of  the  first  sort  if  the  statement  of  difference  is  made 
adequate.  Thus,  '  John  knows  x  Latin ;  James  knows  o  Latin ; 
James  knows  3;  German ;  John  knows  0  German'  should  properly 
replace  the  former  statement.  Similarly  we  have,  '  A  is  imagin- 
ative to  2  extent,  B  is  imaginative  to  2—iv  extent.  B  is  rational 
to  V  extent;  A  is  rational  to  v—w  extent,'  and,  'C  has  r,  y  and  z 
amounts,  respectively,  of  certain  qualities,  certain  degrees  of  which 
in  combination  we  call  the  artistic  temperament;  D  has  small  or 
possibly  zero  amounts  of  these  qualities.'  A  difference  in  human 
nature  then  commonly  is  a  difference  in  the  amount  of  one  thing 
or  an  aggregate  of  differences  each  in  the  amount  of  one  thing. 

But  conceivably  there  may  be  things  which  do  not  vary  in 
amount  except  from  sera  by  a  sudden  jump  to  one  positive 
condition.  The  thing  would  then  either  be  in  one  constant  degree 
or  not  at  all.  The  literature  of  psychology  and  of  education 
abounds  in  cases  of  difference  stated  as  if  the  difference  were 
that  between  0  and  k,  without  k  -  yV>  or  ^  -  tV^  or  k  +  }ik,  etc. 
But  such  statements  are  usually  due  to  ignorance  or  vagueness. 
'  John  is  color  blind  ;  James  is  not '  cannot  really  mean  that  there  is 
some  one  constant  degree  of  color  blindness  which  a  man  either 
has  just  in  that  degree  or  does  not  have  at  all ;  for  there  are 
varying  amounts  of  color  blindness.  In  fact,  it  is  doubtful  if  there 
are  any  individual  differences  in  human  intellect  or  character  of 
this  '  zero  to  k  '  sort. 

When,  therefore,  it  is  stated  that  John  and  James  differ  in 
kind,  the  statement  always,  or  almost  always,  means  nothing  more 
than  that  one  of  the  two  individuals  possesses  a  certain  amount 
or  degree  of  something  of  which  the  other  possesses  0.  When 
it  is  stated  that  the  difference  between  John  and  James  in  one 
thing,  say,  knowledge,  is  qualitative  whereas  their  difference  in 
another,  say,  motor  skill,  is  quantitative,  the  statement  always, 
or  almost  always,  means  nothing  more  than  that  certain  sorts  of 
knowledge,  present  in  certain  amounts  in  John,  are  absent  in 
James,  and  vice  versa ;  whereas,  in  motor  skill,  both  have  percep- 
tible amounts  of  an  identical  set  of  things. 

It  is  then  not  only  permissible,  but  more  scientific  and  more 
useful,  to  think  of  human  individuals  as  all  measured  upon  the 
same  series  of  scales,  each  scale  being  for  the  amount  of  some 
one  thing,  there  being  scales  for  every  thing  in  human  nature,. 


The  Measurement  of  Individual  Differences  5 

and  each  person  being  recorded  as  zero  in  the  case  of  things  not 
appearing  in  his  nature.  And  the  only  problem  of  method  which 
need  concern  us  in  this  chapter  is  the  problem  of  the  nature  and 
use  of  a  scale  for  measuring  different  amounts  or  degrees  of  the 
same  trait  in  different  human  beings. 

Units  and  Scales  for  Measuring  Mental  Differences 

The  facts  of  importance  about  scales  for  mental  and  moral 
traits  can  be  best  stated  in  connection  with  some  concrete  illus- 
trations. 

Consider  the  facts  given  in  Table  I  concerning  individuals 
A,  B  and  C,  with  reference  to  these  questions : — 

1.  What  are   the   differences   between   A   and    B,   A   and   C, 

and  B  and  C  in  each  of  the  traits  ? 

2.  How  many  times  as  great  is  the  difference  between  A  and  B 

in  trait  I  as  that  between  B  and  C  in  trait  I  ?  How  many 
times  as  great  is  the  difference  between  B  and  C  in  trait 
n  as  that  between  A  and  C  in  trait  II,  etc.,  etc. 

What  the  difference  is  between  A  and  B  can  be  definitely  deter- 
mined in  the  case  of  stature  (I),  reaction-time  (II),  error  in 
drawing  a  line  (III),  and  age  (XII)  ;  but  all  that  one  learns 
about  the  differences  in  the  case  of  ability  in  history  (VII)  and 
interest  in  music  (XI)  is  that  one  difference  is  that  between 
excellent  and  good  on  the  arbitrary  scale  of  some  school  and 
that  the  other  is  that  between  little  and  moderate,  in  the  mind 
of  some  observer.  The  measures  of  I,  II,  III  and  XII  are  by 
objective  or  impersonal  scales,  that  is,  scales  the  identification  and 
similar  use  of  which  are  possible  for  any  competent  observer. 
The  measures  of  VII  and  XI  are  by  subjective  or  personal  scales, 
which  another  observer  could  not  identify*  or  use  in  the  way  in 
which  the  person  giving  the  marks  used  them.  Moreover,  what- 
ever the  scales  in  VII  and  XI  really  are,  they  are  certainly  very 
coarse ;  a  wide  range  of  difference  is  expressed  in  them  by  a  few 
steps  or  marks  or  values.  In  short,  any  competent  thinker  knows 
exactly  what  is  meant  by   160  cm.  and  by   160  cm. —  140  cm., 

*If,  for  example,  the  reader  had  heard  the  oral  work  and  seen  the 
written  work  which  in  combination  mean  good  in  the  school  whence 
A  and  B  came,  he  would  not  know  that  they  did  mean  good. 


Educational  Psychology 


TABLE  1. 
Measurements  of  Three  Individuals,  A,  B,  and  C 

ABC 

I.  Stature i6o  cm.        140  cm.       130  cm. 

II.  Simple  reaction-time   to  sound 175  sec.      .125  sec.       .150  sec. 

III.  Average  error  in  drawing  a  line  to 

equal  a  100  mm.  line 3.2  mm.       2.8  mm.       2.2  mm. 

IV.  Number  of  words   (of   a  list   of    12, 

heard  at  a  rate  of  i  per  second) 
remembered  long  enough  to  write 
them   immediately  after  the   last 

word  was  read 6  words       9  words       7  words 

V.  Number  of  examples  in  addition 
(each  of  10  numbers,  repeating  no 
number  in  any  one  example,  taken 
at  random  from  the  numbers  10 

to  99)  done  correctly  in  8  minutes         14  12  18 

VI.  Quality,    or   merit,    or   goodness   of 

handwriting See  Fig,  i    See  Fig.  2    See  Fig.  3 

VII.  School  marks  in  history Ex.  Good  Poor 

VIII.  School  marks  in  spelling 82  62  93 

IX.  Efficiency  in  perception ;  the  number 
of  A's  marked  in  60  seconds  on  a 
sheet  containing   100   A's  mixed 

with  400  other  capital  letters.  ...     48  A's  60  A's         82  A's 
X.  Criminality:    number  of   times  con- 
victed of  a  penal  offense o  i  o 

XI.  Degree  of  interest  in  music little        moderate  a  great  deal 

XII.  Age  in  days 5080  d.        6150  d.        5615  d. 

whereas  he  cannot  be  sure  what  is  meant  by  excellent,  or  by  the 
difference  between  excellent  and  good. 

Concerning  the  other  measurements  the  following  statements 
are  roughly  true : — 

A,  B  and  C  are  measured  objectively  in  the  quality  of  hand- 
writing. We  know  what  is  meant  by  the  difference  between 
A  and  B.  It  is  just  the  difference  between  the  qualities  of  the 
two  samples  presented.  But  they  are  not  measured  conveniently ; 
the  differences  are  not  referred  to  any  commonly  known  scale. 

The  measurement  in  addition  is  nearly  objective.  If  the 
conditions  of  the  test  are  defined  by  a  statement  of  how  the 
examples  were  presented  (what  type  they  were  printed  in,  how 
they  were  arranged,  etc.),  how  the  answers  were  given,  at  what 


The  Measurement  of  Individual  Differences 


8  Educational  Psychology 

time,  under  what  distractions,  with  what  incentives,  etc.,  they 
were  done,  and  the  like,  they  become  still  more  fully  objective. 

In  the  case  of  memory,  not  only  the  conditions  of  the  test,  as 
in  addition,  but  also  the  exact  words  used  need  to  be  specified.  A 
differed  from  B  by  writing  down  three  less  words  of  a  certain 
list.  The  list  needs  to  be  known  if  all  competent  observers  are 
to  think  of  the  same  thing  by  three  words. 

The  measure  of  criminality  is  inferior  to  the  measurement  of 
stature  or  age  by  using  an  ambiguous  unit  (convicted  of  a  penal 
orfense)  and  also  by  measuring  only  very  coarse  differences. 
A  and  C  are  not  differentiated  by  the  measures,  though  A  might 
just  fall  short  of  crime  and  C  be  a  very  healthy-minded  and 
kind-hearted  boy. 

The  measurement  of  ability  in  spelling  might  turn  out  to  be, 
were  the  conditions  of  the  test  and  the  system  of  scoring  results 
in  it  known,  as  objective  as  that  in  addition,  or,  on  the  other 
hand,  may  be  only  a  record  of  the  opinion  of  some  teacher  that 
A  was  a  good  deal  better  than  B  and  that  C  was  somewhat 
above  A.  As  the  record  stands  the  A  —  B  =  20  may  mean  no 
more  than  'A  is  good;  B  is  unsatisfactory,'  or  'A  is  somewhat 
better  than  B  in  my  opinion.' 

The  values  v -^  >  -r p^  and  :^ ^  are  determinable  m  the 

case  of  I,  II,  III  and  XII  of  Table  I.   In  stature  A  —  B  =  20  cm., 

p^ g 

A  —  C  =:  30  cm.  and  -r p^  =  .667.       When  one  says  that  A 

differs  from  C  in  stature  one  and  a  half  times  as  much  as  from  B, 
any  competent  person  knows  exactly  what  is  meant.     For  VII 

,,  ,  ,  A  —  B       Excellent — Good     ,.  , 

on    the    contrary    we    have  -. ^  =  = tz — : =; which 

A  —  C       Excellent  —  Poor, 

may  be  a  true,  but  remains  a  mystical,  answer,  until  excellent,  good 

and  poor  are  defined  on  some  scale. 

In  the  case  of  the  memory  of  words  (A  =  6,  B  =  9,  C  =  y) 

B  — A  J  B  — C 

P        A  —  3  ^^^  Q       j^  =  2 ,  if  to  remember  any  one  word  =  to 

remember  any  other  one  word.  Suppose,  however,  that  the  series 
of  words  was :  '  career,  dilatory,  opium,  never,  soap,  numbers, 
add,  subtract,  one,  two,  three,  four,'  and  that  A  remembered  the 
last  6,  C  the  last  7,  and  B  these  and  the  first  two.     It  would 


The  Measurement  of  Indhidual  Differences  9 

be  very  risky  to  assume  that  the  difference  between  A  and  B  (re- 
membering career,  dilatory  and  numbers)  was  only  three  times 
the  difference  between  A  and  C  (remembering  numbers).  And 
it  would  be  almost  certain  that  a  difference  of  10 — 4  in  the  test 
would  be  really  more  than  twice  as  great  as  a  difference  of  7 — 4. 
Under  the  circumstances  numbers,  add  and  subtract  are  probably 
much  easier  to  remember  than  career,  dilatory  and  opium,. 

In  the  case  of  centimeters  or  seconds  every  competent  person 
knows  not  only  what  fact  is  meant  by  any  given  number  of  the 
units,  but  also  that  any  one  unit  is  equal  to  any  other  one,  any  two 
to  any  other  two,  and  so  on.  In  the  case  of  words  remembered, 
units  called  by  the  same  name  may  not  be  really  equal. 

In  the  case  of  the  addition,  one  example  differed  from  another 
in  difficulty  only  by  chance  and  only  slightly ;  for  when  10  two- 
place  numbers  are  picked  by  chance  and  arranged  in  a  chance 
order,  the  chances  are  enormously  against  getting  any  very  easy 
examples  like   (a)    or  any  very  hard  examples   like    (b). 

(a)  (b) 

25  89 

35  95 

30  58 

40  67 

60  79 

The  chances  are  still  more  against  getting  two  or  three  examples 
in  succession  that  are  on  the  average  more  than  a  trifle  harder 
than  any  other  succession  of  two  or  three.    Reliance  upon  the  truth 

of  — —  =  -—would,  however,  be  safer  if  10,  20,  30,  etc,  and 

C  —  B        6 
II,  21,  31,  etc..  had  been  excluded  from  the  numbers  used  in 

the  tests. 

In  the  case  of  merit  of  handwriting,  the  differences  between 
A  and  B,  B  and  C,  and  A  and  C  do  not  even  pretend  to  be  put 
in  terms  so  as  to  allow  comparison.  As  the  records  stand, 
any  one  must  get  the  differences  transposed  into  terms  of  some 

^ g 

unit  before  he  can  calculate at  all.     Since  the  measures 

A  — C 

of  A,  B  and  C  are  objective,  this  can  be  done.     If,  for  example, 


lO  Educational  Psychology 

the  measurer  could  show  that  the  difference  between  A  and  C 

was  approximately  five-twelfths  of  the  difference  between  two 

standard  samples  accessible  to  all  competent  persons,  and  that  the 

difference  between  A  and  B  was  approximately  two-twelfths  of 

the  dift'erence  between  the  same  two  standard  samples,  he  could 

^ g  ^  k       2 

then  regard  j^ — ^  as,  of  course, ^^-r  or  -,  k  being  the  difference 

between  the  two  standard  samples.  As  a  matter  of  fact  the 
difference  between  the  sample  of  Fig.  i  (p.  7)  and  that  of 
Fig.  3  (p.  7)  is  in  the  combined  opinion  of  some  hundred  judges 
just  about  two  and  one-half  times  as  great  as  the  difference 
between  the  sample  of  Fig.  i  and  that  of  Fig.  2  (p.  7). 

The  sum  and  substance  of  the  last  four  pages  is  that  a  measure- 
ment of  human  nature  to  be  useful  for  our  purpose  must  identify 
the  amount  in  question  for  any  competent  thinker,  just  as  a 
useful  description  must  identify  the  object  in  question.  To  do 
this  it  must  be  objective,  that  is,  free  from  individual  caprice, 
so  that  any  competent  person  making  the  same  measurement 
would  get  the  same  result.* 

It  should  also,  if  possible,  so  state  the  amount  in  question  that 
other  amounts  of  the  same  thing  may  be  compared  with  it  as 
so  much  greater  or  less,  permitting  differences  between  the 
amounts  to  be  expressed  in  ratios.  In  still  briefer  terms,  the 
measurements  should  be  at  defined  points  on  an  objective  scale, 
the  distances  of  these  points  one  from  another  being  also  defined. 

The  reason  for  the  elaborate  introduction  to  and  illustrations 
of  this  obvious  principle  is  that  in  its  application  to  particular 

*Not,  of  course,   exactly  the  same.     There  is  a  personal   equation   in 

even  the  most  objective  measures,  such  as  the  length  of  this  Hne . 

If  they  measured  it  to  thousandths  of  a  milHmeter,  competent  observers 
would  not  get  the  same  result,  except  by  chance.  Nor  would  the  same 
observer  in  several  independent  measurements.  The  ultimate  distinction 
between  objective  and  subjective  is  simply  that  in  the  former  sort  of 
measurements  competent  observers  use  very  nearly  the  same  criteria  and, 
the  independent,  agree  very  closely,  whereas  in  the  latter  they  use  very 
different  criteria  and,  if  independent,  agree  only  roughly.  The  reader  may 
safely  postpone  any  subtle  or  thoroughgoing  treatment  of  the  distinction 
until  he  can  study  the  theory  of  mental  measurements  in  detail.  For  the 
purposes  of  this  book,  objective  measures  may  be  defined  as  measures 
which  competent  observers  could  repeat  and  verify  or  reject,  and  subjective 
measures  as  measures  which  they  could  not  so  repeat  and  verify. 


The  Measurement  of  Individual  Differences  ii 

problems  in  the  study  of  educational  psychology  it  has  not  been 
obvious  to  even  the  writers  of  treatises  and  investigators  of 
original  data,  much  less  to  the  rank  and  file  of  students  of 
psychology  or  of  education.  On  the  contrary  this  entire  chapter 
would  not  suffice  to  list  and  barely  describe  the  quantitative  con- 
clusions that  have  been  drawn  from  subjective  opinions  or  from 
the  acceptance  as  equal  of  units  which  happened  to  be  called  by 
the  same  name. 

The  reason  for  contrasting  physical  and  mental  measurements, 
to  the  apparent  disrepute  of  the  latter,  is  not  that  I  wish  to  dis- 
courage the  reader  from  trusting,  or  from  making,  measurements 
of  any  feature  whatever  of  intellect  or  character.  It  is  to  be 
hoped,  however,  that  he  \\\\\  be  effectually  discouraged  from 
trusting  measurements  which  do  not  deserve  trust.  The  lesson 
to  be  drawn  from  the  contrast  is  that  a  measurement  can  rightly 
be  trusted  or  rejected  or  criticized  or,  indeed,  understood,  only 
if  the  concrete  reality  which  it  describes  is  known.  Any  numerical 
statement  has  meaning  only  in  reference  to  a  concrete  scale  and 
its  units. 

The  Variability  of  a  Mental  Measurement 

One  cause  of  improper  distrust  of  measurements  of  intellect 
and  character  is  so  common  that  it  demands  special  treatment. 
This  is  the  variability  of  the  same  measurement  of  apparently 
the  same  fact.  For  instance,  individual  A  was  tested  by  hearing 
a  series  of  12  letters  read  at  a  rate  of  2  per  second,  he  being 
required  to  write  down  as  many  as  he  could  remember  in  theii; 
proper  order  as  soon  as  the  reading  was  finished.  His  score 
was  4  correct  in  one  trial  and  10  correct  in  another,  the  two 
letter-series  being,  for  people  in  general,  of  equal  difficulty.  What 
assurance,  it  may  be  said,  can  be  felt  in  a  measurement 
of  now  4  and  now  10  for  the  same  fact?  The  defense  is  that 
it  is  not  the  same  fact.  To  measure  A's  memory  for  series  of 
letters  is  not  to  measure  one  constant  thing,  but  a  very  variable 
thing.  A,  as  regards  taking  in  and  holding  a  series  of  letters, 
is  not  the  same  from  moment  to  moment.  What  is  measured  in 
one  trial  is  a  sample  of  A's  varying  status  in  respect  to  this 
ability.  His  first  score  in  the  measurement  in  question  was  4. 
This  measurement  is,  so  far,  so  good ;  it  is  better  to  believe  that 


12 


Educational  Psychology 


A's  ability  in  that  test  is  4  than  to  guess  at  it.     In  a  second  test 
the  score  was  10. 

To  say  that  A's  ability  is  4  or  10  or  averages  7  is  better  than 
to  have  taken  the  4  as  a  measure.  But  further  trials  give 
(including  these  two) 


y 


I  record  of  4 

letters  correct 

4  records 

"  5 

4       " 

"  6 

7      " 

"7 

13       " 

"  8 

3      " 

"9 

4      " 

"10 

From  all  these  scores  we  get,  as  an  average,  7.44  letters 
correctly  written ;  as  the  most  common  record  (the  so-called 
Mode),  8  letters  correctly  written.  Since  a  record  of  4  letters 
correctly  written  means,  perhaps,  4^/2  letters  remembered,  one 
of  5  letters  correctly  written,  53^  letters  remembered  and  so  on, 
we  should  perhaps  call  A's  average  memory  letters  7.94  and  his 
mode  or  most  frequent  performance  8.5.* 

Now  the  trustworthiness  of  any  one  of  these  is  6  times  as  great 
as  that  of  the  first  single  score  4.^  But  we  can  not  be  sure 
that  the  average  of  the  36  measurements  is  identical  with  A's 
true  average  ability.  In  fact  we  can  be  almost  sure  that  it  is 
not.  Seventy-two  measurements  might  give,  and  almost  certainly 
would  give,  a  slightly  different  average.  True  average  ability 
in  the  case  of  variable  measurements  means  the  measure  we 
would  get  as  an  average  from  an  infinite  number  of  measure- 
ments. Only  by  chance  will  the  result  from  any  finite  number 
of  measurements  be  identical  with  it.    All  our  measures  represent 

*If  an  individual  writes  7  letters  correctly,  but  does  not  write  an  eighth, 
it  means  that  he  remembered  at  least  7  and  not  8.  The  measurement  is 
comparable  to  one  of  length  in  which  the  observer  notes  that  a  stick  is 
over  62  inches,  and  is  not  63  inches,  long.  And  just  as,  in  the  long  run, 
sticks  62  inches  or  over  but  not  63  inches  or  over  will  average  62V3  inches, 
so  the  person  remembering  on  many  occasions  at  least  7  but  not  8  letters 
will  average  yVz  letters.  Some  of  his  records  of  7  mean  7  letters  remem- 
bered and  one  more  letter  almost,  but  not  quite,  remembered. 

fit  is  found  in  variable  measurements  of  the  ordinary  sort  that  the 
reliability  of  an  average  increases  as  the  square  root  of  the  number  of 
measurements  taken. 


The  Measurement  of  Individual  Differences 


13 


approximations,  but  the  greater  the  number  of  measures  the  closer 
the  approximation  will  be. 

The  series  of  measures  above  is  our  knowledge  of  A's  ability. 
We  can  see  the  fact  more  clearly  by  expressing  it  in  space  rather 
than  in  figures.  If  we  let  each  quarter  inch  along  a  horizontal 
line  stand  for  one  letter  correctly  written,  and  each  eighth  of 
an  inch  of  height  above  it  stand  for  one  manifestation  by  A 
of  the  ability  designated  by  that  place,  we  have  Fig.  4,  by  which 
one  can  see  at  a  glance  A's  ability,  its  variability  and  his  general 
tendency  to  keep  nearer  8  than  any  other  one  ability. 


4     5 


6     7      8     9    10 

Fig.  4.     The  ability  of  individual 
A  in  memory  of  letters. 


5     6     7      8     9 

Fig.  5.     The  ability  of  individual 
B  in  memory  of  letters. 

If  we  must  for  any  reason  abbreviate  our  description  of  A's 
ability  we  may  best  take  two  measures,  one  of  the  ability  about 
which  his  various  scores  center  most  closely  and  the  other  of  the 
closeness  of  his  grouping.  We  may  term  these  the  central  tendency 
and  the  variability.  For  the  former  the  average  or  median"^  or 
mode  may  be  used,  for  the  latter  the  average  of  the  differences 
between     the     individual     records    and"  their    central    tendency 

*The  Median  has  two  meanings  :  the  point'oh.  the  scale  above  and  below 
which  equal  per  cents  of  the  individual  scores  lie,  and  the  mid  measure, 

that   is,   the    ^  '    ^  th   measure,   counting  in  from  either   extreme,  where 

2 
n  =  the  total  number  of  measures.     These  two  definitions   lead  to   sub- 
stantially the  same  results,  and  for  present  purposes  the  reader  may  adopt 
either  one.     Indeed  it  will  do  no  harm  if  he  can  see   no   difference   between 
the  two. 


14  Educational  Psychology 

(Average  Deviation  or  A.D.),  or  any  one  of  a  number  of  measures 
of  the  closeness  of  clustering  of  the  individual  records  about  their 
central  tendency. 

Let  us  suppose  that,  with  the  same  test,  individual  B  showed 
the  following  ability: 

correct. 


2 

records  of  5 

3 

6 

II 

"         7 

17 

8 

3 

"         9 

This  is  shown  graphically  in  Fig.  5.  The  average,  median 
and  mode  would  be  closely  the  same  as  for  A,  but  the  variability  of 
the  measures  would  be  less.  The  limits  for  A  were  4 — 10.  For 
B  they  are  5 — 9.  The  average  difference  of  the  individual 
measure  from  the  mode  for  A  was  1.17.  For  B  it  is  0.7.  B's 
ability  has  the  same  central  tendency  as  A's,  but  B  is  a  more 
constant  performer. 

It  is  obvious  that  an  average  from  a  set  of  measurements  like 
the  second  is  less  likely  to  deviate  from  the  true  status  than  an 
average  from  a  set  like  the  fiirst.  And  in  general  the  less  the 
variability  of  the  single  measures  the  greater  the  reliability  of  the 
result  inferred  from  them. 

In  the  case  of  A's  memory  we  should  say,  using  formulae  the 
derivation  of  which  need  not  be  described  here:  From  what 
knowledge  we  have,  the  most  likely  true  average  number  of  letters 
correctly  written  for  A  is  7.44 ;  the  chances  are 

1  to  I  that  the  true  average  does  not  differ  from  7.44  letters  correctly 

written  by  more  than  .171 

2  to  I  that  the  true  average  does  not  differ  from  7.44  letters  correctly 

written  by  more  than  .245 

3  to  I  that  the  true  average  does  not  differ  from  7.44  letters  correctly 

written  by  more  than  .291 
99  to  I  that  the  true  average  does  not  differ  from  7.44  letters  correctly 
written  by  more  than  .651 
999  to  I  that  the  true  average  does  not  differ  from  7.44  letters  correctly 
written  by  more  than  .835 

The  variability  of  mental  measurements  thus  gives  no  reason 
to  distrust  them,  but,  on  the  contrary,  gives  a  means  of  knowing 
just  how  trustworthy  they  are. 


The  Measurement  of  Individual  Differences 


15 


Methods    of   Reporting    Individual    Differences    Withiri    Large 

Groups 

Suppose  now  that  the  average  ability  in  remembering  letters 
in  such  a  test  as  that  described  had  been  determined  for  every 
human  being  six  years  old  or  older.  From  such  records  the 
difference  of  any  individual  from  any  other  could  be  computed, 
but  only  by  hunting  out  the  records  of  the  two  individuals.  The 
frequency  of  any  given  degree  of  difference  could  be  found  a 
very  simple  summary  of  such  records,  such  as  appears  in  Table  2. 


TABLE  2 

Supposed  Distribution  of  Average  Ability  to  Remember  Letters  in 
THE  Case  of  Human  Individuals  Six  Years  Old  or  Older 


An  average  of    o  letters  was  remembered  by 

1  letter      "  "  " 

2  letters    "  "  " 

3  " 

4  " 
5 
6       " 

7 


9 
10 


13 
14 
15 
16 

17 
18 

19 
20 


o  individuals 

2,000,000  " 

30,000,000  " 

60,000,000  " 

190,000,000  " 

280,000,000  " 

360,000,000  " 

310,000,000  " 

190,000,000  " 

40,000,000  " 

6,000,000  " 

400,000  " 

100,000  " 

40,000  " 

20,000  " 

4,000  " 

500 

100  " 

5 

o  " 

o  " 


A  difference  of  17  occurs  only  io,(XX),oo  times,  between 
each  of  the  individuals  of  ability  18  and  each  of  the  2,000,000 
of  ability  i.  A  difference  of  16  occurs  350.000,000  times 
(5  times  30,000,000+100  times  2,000,000).  A  difference  of  15 
occurs  4,300,000,000  times  (5  times  60.000.000+100  times 
3,000,0004-500  times  2.000,000). 

A  distribution  or  table  of  the  frequencies  of  the  abilities  of 


i6 


Educational  Psychology 


individuals  is  then  a  convenient  means  of  presenting  the  facts 
from  which  the  frequencies  of  the  different  differences  amongst 
them  may  be  calculated.  It  serves  many  other  purposes  as  well, 
and  so  is  commonly  used  in  reporting  the  results  of  the  measure- 
ment of  any  one  trait  in  a  number  of  individuals.  The  main 
features  of  such  a  table  can  be  seen  at  once  in  their  relations 
one  to  another  if  it  is  presented  in  graphic  form.  Thus 
Table  2  becomes  Fig.  6,  by  letting  the  amounts  of  the  trait  be 
represented  along  a  horizontal  line  and  the  number  of  persons 
possessing  each  amount  be  represented  by  the  heights  of  a  column 


10— 


0   1   2    8   4    5   6    7    8    9  10  H  18113 


18 


Fig.  6.  Relative  frequencies  of  the  different  abilities  in  remembering 
letters  of  human  individuals  six  years  old  or  older.  The  horizontal  scale  is 
for  the  average  number  of  words  remembered.  The  vertical  scale  is  for  the 
number  of  individuals,  10,000,000  being  the  unit. 


erected  at  the  place  on  the  scale  denoting  that  amount.  Such  a 
graphic  representation  is  called  a  surface  of  frequency  or  a  surface 
of  distribution;  the  line  which,  with  the  base — or  scale — line, 
encloses  this  surface  is  called  a  frequency  curve  or  distribution 
curve. 

No  one  has  measured  all  human  beings  or  even  a  small  but 
fair  sampling  of  all  human  beings  in  even  a  single  mental  trait. 
Nor,  as  we  shall  see,  would  that  be  a  very  useful  undertaking. 
If  there  were  such  measurements, — if,  for  example,  Table  2  and 
Fig.  6  represented  actual  facts, — they  would  emphasize  the 
problem,  which  should  be  emphatic  enough  without  them,  of 
accounting  for  every  difference  existing.    They  would  also  make 


The  Measurement  of  Individual  Differences  17 

it  easier  to  see,  what  is  already  clear  enough,  that  accounting  for 
every  difference  is  the  same  as  accounting  for  each  person's 
position  on  the  scale, — each  person's  amount  of  the  trait.  It  is 
this  problem  of  the  causes  of  individual  differences  or  the  causes 
of  each  individual's  amount  of  each  trait  that  is  to  occupy  our 
attention  in  the  next  five  chapters. 


CHAPTER   III 

The  Influence  of  Sex 

Preliminary  Cautions 

By  way  of  preface  to  an  account  of  sex  differences  it  is  well 
to  note  that  their  existence  does  not  necessarily  imply  in  any 
case  the  advisability  of  differences  in  school  and  home  training, 
and,  on  the  other  hand,  that  even  if  the  mental  make-up  of  the 
sexes  were  identical  it  might  still  be  wisest  to  educate  them 
differently.  It  is  true  that  a  difference  of  two  groups  in  a  mental 
trait  will  theoretically  involve  dift'erences  in  treatment,  but  prac- 
tical considerations  apart  from  that  of  developing  the  highest 
efficiency  in  that  trait  may  outweigh  the  advantages  of  the  differ- 
ential treatment.  For  instance,  consumptives  theoretically  need  a 
different  mode  of  life  from  people  with  healthy  lungs,  but  it 
might  in  some  cases  be  wiser  to  leave  a  consumptive  to  his 
ordinary  habits  rather  than  to  cause  in  him  consciousness  of  his 
disease  and  worry  concerning  it.  On  the  other  hand,  two  boys 
might  be  identical  in  mental  structure,  yet  their  education  might 
best  be  very  different  if  we  wished  to  make  one  of  them  a 
chemist  and  the  other  a  psychologist. 

Let  us  note  in  the  second  place  that  the  existence  of  differences 
need  not  imply  the  need  of  different  training,  because  those 
very  differences  may  have  been  due  to  the  different  training 
actually  received  and  might  never  have  appeared  had  training 
been  alike  in  the  two  classes.  It  is  folly  to  argue  from,  any 
mental  condition  in  an  individual  or  class  without  ascertaining 
whether  it  is  due  to  original  nature  or  to  training. 

The  chapter  should  properly  be  devoted  exclusively  to  the 
dift'erences  necessarily  produced  by  sex.  Those  produced  by 
virtue  of  the  adventitiously  different  training  which  boy  and  girl 
undergo  belong  in  chapter  VII.        So  far  as  may  be,  such  a 

(i8) 


The  Influence  of  Sex  19 

separation  of  differences  due  to  sex-nature  from  those  due  to 
our  traditional  treatment  of  the  sexes  is  in  fact  made.  But  in 
many  cases  where  the  amount  of  the  difference  that  is  to  be 
credited  to  training  is  doubtful,  the  difference  will  be  described 
in  the  present  chapter,  the  discount  to  be  made  being  left  to  the 
reader's  judgment. 

A  further  caution  is  necessary  before  this  description  and 
incomplete  analysis  begins.  It  is  not  to  confuse  differences  in 
behavior,  achievement  and  mental  activities  indirectly  caused  by 
physical  traits  with  such  differences  directly  caused  by  mental 
traits.  Lack  of  muscular  strength  and  the  phenomena  intimately 
associated  with  bearing  children  may  serve  as  samples  of  such 
physical  traits.  Even  if  women  possessed  mental  capacities  for 
business  identical  with  those  of  men,  they  still  might  not  in  active 
work  do  as  much. 

In  the  fourth  place  the  fallacy  of  unfair  selection  must  not  be 
forgotten  in  our  comparisons  of  men  and  women.  For  instance, 
any  inference  from  a  comparison  of  young  men  and  women  in 
college  or  of  working  women  with  men  in  the  same  profession  is 
untrustworthy.  College  women  and  college  men  are  two  classes 
selected  by  different  agencies.  The  intellectual  impulse  has  been 
relatively  a  more  powerful  agent  in  sending  girls  to  college, 
while  convention  and  the  demand  for  a  pleasant  social  and 
athletic  life  have  acted  more  powerfully  on  boys.  In  the  case 
of  an  industry,  say  laundering,  women  are  selected  by  relative 
ignorance,  strength,  widowhood,  drunken  husbands,  etc.,  while 
the  men  are  selected  largely  by  Chinese  birth.  Let  not  the 
bizarre  nature  of  this  particular  illustration  blind  us  to  the  fact 
that  women  and  men  physicians,  lawyers,  stenographers,  teachers 
or  government  clerks  represent  different  samplings  of  the  two 
sexes.  It  is  possible  theoretically  to  make  a  discount  for  the 
differential  influence  of  selective  agencies  and  thus  permit  a  fair 
comparison,  but  the  amount  of  the  discount  is  very  hard  to 
determine. 

The  investigator  of  the  direct  share  of  sex  in  the  production 
of  mental  differences  would  like  to  compare  individuals  alike  in 
age,  race,  immediate  ancestry  and  training,  different  in  sex  alone. 
The  nearest  approach  that  he  can  make  to  this  crucial  comparison 
is  to  compare  a  brother  with  his  twin  sister  in  the  case  of  families 


20  Educational  Psychology 

where  the  treatment  of  the  two  is  most  alike.*  What  he  has 
done  is  to  take  such  measurements  as  he  can  get,  of  boys  and 
girls  or  men  and  women  as  nearly  alike  in  age  and  race  and 
training  as  practical  exigencies  allow,  and  to  measure  enough 
individuals  to  make  the  average  immediate  ancestry  of  the  one 
group  nearly  like  that  of  the  other. 

A  Sample  Study  of  the  Influence  of  Sex 

I  shall  report  as  a  sample  of  such  studies,  that  of  Dr.  Thompson. 
[Thompson,  H.  B.,  '03]  This  report  will  be  followed  by  a  state- 
ment of  present  knowledge  concerning  sex  differences,  first  in 
intellectual  or  semi-intellectual  abilities,  including  sensory  and 
motor  abilities,  and  then  in  those  interests,  tendencies  and  propen- 
sities which  constitute  what  we  roughly  call  character  and  tem- 
perament. 

Dr.  Thompson  describes  the  essential  arrangements  made  by 
her  to  secure  a  just  measurement  of  sex  differences,  as  follows : — 
['03  ;  pp.  2-6,  passim] 

"  In  order  to  make  a  trustworthy  investigation  of  the  varia- 
tions due  to  sex  alone,  therefore,  it  is  essential  to  secure  as 
material  for  experimentation,  individuals  of  both  sexes  who  are 
near  the  same  age,  who  have  the  same  social  status,  and  who 
have  been  subjected  to  like  training  and  social  surroundings.  The 
complete  fulfilment  of  these  conditions,  even  in  the  most  demo- 
cratic community,  is  impossible.  The  social  atmosphere  of  the 
sexes  is  different  from  the  earliest  childhood  to  maturity. 
Probably  the  nearest  approach  among  adults  to  the  ideal  require- 
ment is  afforded  by  the  undergraduate  students  of  a  coeducational 
university.  For  most  of  them  the  obtaining  of  an  education  has 
been  the  one  serious  business  of  life.  They  have  had  at  least 
the  similarity  of  training  and  surroundings  incident  to  school  life. 

*I  have  made  this  comparison  in  the  case  of  ten  pairs  of  twins  from 
9  to  15  years  old,  in  simple  but  fairly  precise  tests  of  efficiency  in  perceiving 
small  details  (A  test,  a-t,  r-e,  and  misspelled  vvrord  tests)  and  of 
efficiency  in  controlled  associations  of  ideas  (opposites  test,  addition  and 
multiplication).  The  difference  between  boy  and  girl  of  a  pair  of  twins 
varies  greatly,  but  the  general  result  is  an  absence  of  difference,  the  boys- 
doing  worse  by  i  per  cent  in  the  former  and  better  by  2  per  cent  in  the 
latter  tests.  This  general  result  might  change  if  ten  thousand  instead  of 
ten  pairs  were  studied,  but  the  chances  are  over  9  out  of  10  that  there- 
would  not  be  a  difference  of  15  per  cent  in  favor  of  either  sex. 


The  Influence  of  Sex  21 

Most  of  those  in  a  western  university  have  received  their  education 
in  coeducational  schools. 

The  individuals  who  furnished  the  basis  for  the  present  study 
were  students  of  the  University  of  Chicago.  They  were  all  juniors, 
seniors,  or  students  in  the  first  year  of  their  graduate  work.  The 
original  intention  was  to  limit  the  ages  to  the  period  from 
twenty  to  twenty-five  years.  Owing  to  the  difficulty  of  obtaining 
a  sufficient  number  of  subjects  within  these  limits,  a  few 
individuals  of  nineteen  years,  and  a  few  over  twenty-five  were 
admitted.  The  subjects  were  obtained  by  requesting  members 
of  the  classes  in  introductory  psychology  and  ethics  to  serve. 
They  were  told  nothing  about  the  object  of  the  tests  except  that 
they  were  for  the  purpose  of  determining  psychological  norms. 

The  series  of  questions  on  age,  health  and  nationality, 

shows  that  in  all  these  respects  the  men  and  women  tested  were 
closely  comparable 

The  series  of  tests  employed  in  this  investigation  required 
from  fifteen  to  twenty  hours  of  time  from  each  subject.  The 
hours  were  arranged  from  one  sitting  to  the  next  according  to 
the  convenience  of  the  subject.  It  was  not  possible  to  have  the 
hours  for  any  one  test  constant  for  all  subjects,  since  the  schedules 
varied  so  widely.  No  attempt  was  made  to  keep  the  order  of 
experiments  rigidly  the  same  for  all.  Convenience  and  economy 
of  time  necessarily  determined  the  order  to  a  great  extent.  In 
general,  however,  the  simple  sensory  and  motor  tests  were  given 
in  the  early  part  of  the  series,  and  the  intellectual  tests  in  the 
latter  part.  The  questions  on  personality  usually  came  last. 
The  taste  and  smell  experiments  had  to  be  scattered  through 
most  of  the  periods,  since  only  a  few  at  a  time  could  be  performed 
without  fatigue.  The  entire  series  was  applied  to  fifty  subjects, 
twenty-five  men  and  twenty-five  women. 

The  experiments  fell  into  seven  groups,  dealing  respectively 
with  motor  ability,  skin  and  muscle  senses,  taste  and  smell, 
hearing,  vision,  intellectual  faculties,  and  affective  processes.     .  .  . 

A  few  words  in  general  on  the  methods  employed  may  not 
be  out  of  place,  in  spite  of  the  fact  that  each  is  described  in 
full  in  connection  with  the  test.  The  guiding  principle  in  selecting 
the  method  was  the  desire  to  make  the  directions  to  the  subject 
as  clear  and  simple  as  possible  and  at  the  same  time  secure  the 
greatest  possible  accuracy  of  result." 


22 


Educational  Psychology 


The  following  quotations  give  an  idea  of  details  of  method  in 
the  case  of  two  of  the  tests  of  "  intellectual  faculties " : — 
[Thompson,  '03,  pp.  111-114] 

Test  I  for  Ingenuity 

"  Fifteen  matches  were  laid  on  the  table  in  such  a  way  that 
they  formed  five  squares  in  the  relative  position  shown  in  Fig.  7. 
The  subject  was  then  asked  if  he  had  ever  seen  the  figure  before 
or  knew  its  purpose.  One  of  the  fifty — a  woman — had  seen  it 
before,  but  had  forgotten  its  purpose.  She  found  the  solution  in 
ten  seconds,  but  since  she  was  doubtless  assisted  by  her  previous 
acquaintance  with  the  figure,  her  record  is  not  included  in  the 
curve.        The  others,  upon  stating  that  they  had  no  previous 


Fig.  7. 

knowledge  of  the  figure  or  its  purpose,  were  told  that  the  problem 
was  to  remove  three  matches  from  it  in  such  a  way  that  three 
perfect  squares  only  remained ;  in  other  words,  to  remove  three 
matches  in  such  a  way  that  every  match  remaining  on  the  table 
after  the  three  were  removed  should  be  a  part  of  a  perfect  square. 
No  rearranging  of  the  remaining  matches  was  allowed.  The 
subjects  were  all  given  exactly  the  same  directions,  and  were 
left  entirely  free  to  use  any  method  they  chose.  Removing 
matches  on  trial  was  perm^itted.       Time  was  counted  from  the 

moment  the  conditions   were  understood 

The  second  ingenuity  test  was  designed  to  call  a  pure  process 
of  reasoning  into  play.  It  consisted  of  a  puzzling  mathematical 
problem,  perfectly  simple  in  the  computations  involved  but 
demanding  a  somewhat  complicated  process  of  reasoning  for  its 
solution — a  problem  in  which  it  was  easy  to  become  confused 
unless  all  the  factors  were  sharply  separated  and  clearly  grasped. 
The  problem  was  handed  written  to  the  subject.  He  was  told 
that  it  involved  no   difficult  computations.        The  process   was 


The  Influence  of  Sex  23 


6  + 
5  • 

H       + 
3    «• 


fi  1 1 1  nil  1 1 1        I 1         I r- 

011345678110      1^     U     IS     iO     35 
e 


3        •  +  +  • 

2 

J     4  +  •      + 


r"i   I   I   I   t   I  I   I   I   I 1 1 1 1 1 1 1  T" 

0  2  U  no  12  If  IG  ino     15     30      i5     10     iS      so     55  * 


0      5      10      15     20      B     30     35     10      15     50     55     60     W"     IS  P 

Figs.  8,  9  and  10.  Comparison  of  men  and  women  in  respect  to  three  tests 
of  ingenuity.  The  horizontal  scales  are  for  the  time  ( in  minutes )  taken  to 
solve  the  problem.  The  vertical  scales  are  for  the  number  of  individuals. 
The  height  of  a  dot  represents  the  number  of  men  whose  times  fell  within  the 
division  of  the  scale  above  whose  right  limit  the  dot  stands.  The  height  of 
a  cross  has  the  same  meaning,  but  for  women.  Thus  ( in  the  middle  diagram  ) 
4  men  and  i  woman  took  from  o  to  2  minutes,  3  men  and  i  woman  from  2 
to  4  minutes,  3  women  and  i  man  from  4  to  6  minutes,  in  the  second  test  in 
ingenuity. 

Fig.  8  ( at  the  top  )  records  the  results  in  the  first  test  of  ingenuity. 

Fig.  9  (in  the  middle )    "      "         "       "     "  second  test  of  ingenuity. 

Fig.  10  ( at  the  bottom  )  "      "         "       "     "  third  test  of  ingenuity. 


24  Educational  Psychology 

timed  from  the  moment  the  problem  had  been  read  through.  A 
failure  was  recorded  only  in  cases  in  which  the  subject  had 
worked  from  forty-five  minutes  to  an  hour,  and  was  completely 
hopeless  of  getting  any  solution.  The  problem  was  the  following : 
'  A  man  swimming  in  a  river  finds  that  he  can  swim  three  times 
as  fast  down  stream  as  up  stream.  The  river  flows  at  the  rate 
of  a  mile  an  hour.  Find  his  rate  of  swimming  in  still  water.' 
Any  solution  which  could  be  explained  was  accepted.  A  mere 
stumbling  upon  the  correct  answer  was  not  called  a  solution." 

The  third  problem  was  to  place  eight  counters  on  a  checker- 
board of  64  squares  so  that  no  two  counters  were  on  the  same 
horizontal,  vertical  or  diagonal  row  of  squares. 

The  results  of  these  three  tests  are  shown  by  Dr.  Thompson  in 
the  curves  reproduced  in  Figures  8,  9  and  10. 

Means  of  Measuring  the  Differences  Between  Two  Groups 

These  distribution  curves  show  fully  the  differences  between 
the  men  and  the  women,  but  they  do  not  show  them  very  con- 
veniently. For  convenience  in  comparing  the  difference  in,  say, 
the  second  of  these  tests  of  ingenuity  with  the  difference  in  the 
third  or  in  comparing  the  difference  in  any  one  of  them  with 
the  difference  in  memory  or  accuracy  of  movement  or  rate  of 
association,  the  difference  in  any  one  trait  should  be  represented 
by  some  one  amount. 

There  are  two  ways  of  representing  the  difference  between  two 
groups  by  one  amount.  The  first  is  by  stating  the  difference 
between  the  two  central  tendencies.  Thus  in  the  second  test 
above  the  two  tables  of  frequency  are  as  in  Table  3.  The  average 
is  not  here  a  suitable  measure  of  the  central  tendency  since 
'  failed  '  cannot  be  given  a  numerical  value.*  There  is  no  clear 
mode  for  either  men  or  women.  The  median  is  however  a  useful 
measure  here.  The  median,  in  the  sense  of  the  point  on  the 
scale  which  will  have  half  of  the  men's  records  above  it  and  half 
below,  is  somewhere  between  12  minutes  and  14  minutes.  Just 
where  it  is  for  these  25  men  cannot  be  stated  since  we  do  not 
know  the  exact  records  of  the  three  men  who  took  from  12  to  14 
minutes.  It  would  be  at  the  point  of  the  quickest  of  these  three 
men.     The    most    probable    place    for    him    is    from  12  to  I2§ 

*AIso  for  other  reasons. 


The  Influence  of  Sex 


25 


TABLE  3 

Comparison  of  Men  and  Women  in  Ingenuity — Second  Test 
Frequencies  of  Different  Times  Taken  in  Solving  the  Problem 


Men 

Women 

0  to 

2  minutes  was 

required  by 

4      and        I 

2    " 

4 

3 

'          I 

4  " 

6 

I 

3 

6  " 

8 

0 

3 

8  " 

10 

3 

'          I 

ID    " 

12 

I 

0 

12     " 

14 

3 

0 

14    " 

16 

0        ' 

4 

16    " 

18 

0        ' 

0 

18    " 

20 

0        ' 

'          2 

20    " 

25 

I         ' 

'          I 

25    " 

30 

I         ' 

2 

30    " 

35 

I         ' 

'          I 

35  " 

40 

0        ' 

'          I 

40  " 

45 

0        ' 

'          0 

45  " 

50 

0        ' 

'          0 

50  " 

55 

"          " 

I         ' 

'          0 

Failed  in 

45  to  60  minutes 

6 

5 

The  median 

man  required 

12^  minutes 

the   median    woman, 

minutes. 

15H 


minutes.  The  midpoint  of  this  place  is  12^  minutes.  The 
median  for  women  is  the  slowest  of  the  4  records  in  the  14-16 
minute  group.  The  most  probable  point  for  this  is  15^  minutes. 
The  median  man  is  thus  3^  minutes  quicker  than  the  median 
woman  in  this  test  and  requires  only  8  tenths  as  long  as  she.  In 
the  third  test  of  ingenuity  the  median  man  is  the  slowest  one  of 
the  three  taking  from  20  to  25  minutes,  while  the  median  woman  is 
the  quicker  one  of  the  two  taking  from  60  to  65  minutes.  The 
most  probable  points  for  them  are  respectively  24.17  and  61.25.  The 
median  man  is  thus  37.08  minutes  quicker  than  the  median  woman 
in  test  3  and  requires  only  4  tenths  as  long. 

The  second  method  of  representing  the  difference  between  two 
groups  by  one  amount  is  by  stating  the  per  cent  of  one  group 
that  reaches  or  exceeds  a  given  record  made  by  some  one  of 
the  other  group.  Thus  in  the  second  test  of  ingenuity  60  per  cent 
of  men  reach  or  exceed  (that  is,  are  quicker  than)  16  minutes, 
which  is  reached  or  exceeded  by  52%  of  women.  48%  of  men 
reach  or  exceed  12  minutes,  which  is  reached  or  exceeded  by 
36%   of  women.        The  particular  comparison  of  this   sort  of 


26  Educational  Psychology 

most  service  is  the  per  cent  of  group  i  reaching  or  exceeding, 
the  median  of  group  2.  In  test  2,  60%  of  men  reach  or  exceed 
the  median  for  women.  In  the  case  of  the  third  test  69%  of 
men  reach  or  exceed  the  median  for  women. 

The  great  advantage  gained  by  comparing  groups  by  the  per 
cent  of  one  group  reaching  or  exceeding  the  point  on  the  scale 
that  is  reached  or  exceeded  by  a  given  per  cent  of  the  other 
group  is  that  results  are  mutually  comparable  whatever  the  traits 
may  be.  In  place  of  a  list  of  differences  now  in  time  taken,  now 
in  amount  done,  now  in  quality  of  this  product,  now  in  the  amount 
of  that  error  made,  etc.,  etc.,  the  second  method  gives  a  simple 
list  of  per  cents  of  men  who  reach  the  median  for  women.  Another 
advantage  lies  in  the  fact  that  this  percentile  comparison  reminds 
one  constantly  of  the  overlapping  of  the  two  groups,  when  such 
exists. 

This  second  method  should,  therefore,  be  used  in  the  statement 
of  sex  differences,  and  may  be  used  exclusively  for  very  small 
differences  and  differences  measured  in  ambiguous  units  such  as 
school  and  college  marks. 

Unfortunately,  of  the  investigators  who  have  made  mental 
measurements  of  men  and  women,  few  have  realized  the  need  of 
presenting  the  distribution  of  the  trait  in  question  for  each  sex, 
and  still  fewer  have  calculated  the  per  cent  of  one  group  passing 
the  point  passed  by  half  (or  by  any  other  assigned  per  cent)  of 
the  other  group.  Many  of  the  measurements  of  sex  differences 
thus  remain  incommensurate  with  the  rest  and  are  incapable  of 
inclusion  in  an  exact  general  estimate. 

Dr.  Thompson  does  give  the  entire  distributions  so  that  we  can 
summarize  the  essential  features  of  her  results  in  the  following 
table  (Table  4)  :— 

The  Results  of  Measurements  of  Sex  Differences 

In  examining  Table  4  and  similar  results  it  will  be  'nstruc- 
tive  to  have  clearly  in  mind  the  significance  of  different  per 
cents  of  one  sex  reaching  or  exceeding  the  median  of  the  other 
sex.  50  means  of  course  that  the  central  tendencies  of  the  two 
sexes  are  identical. 

45  or  55  means  the  amount  of  difference  shown  in  Fig.  11. 

40  or  60  means  the  amount  of  difference  shown  in  Fig.  12. 

25  or  75  means  the  amount  of  difference  shown  in  Fig.  13. 


The  Influence  of  Sex  27 

TABLE  4. 

Differences   between   Young   Men   and   Young    Women   in   Various 

Mental  Processes. 

In  the  case  of  50  students  in  the  University  of  Chicago  of  approximately 
equal  age  and  academic  status  the  per  cent  of  men  reaching  or  exceeding 
the  median  of  the  women  is  as  follows: — 

In  reaction  time 68 

Rate  of  tapping  with  finger  for  first  20  seconds 81 

"     "          "          "         "       "    last  20      "        of  120* 81 

Sorting  cards  by  color;  speed 14 

"           "        "        "       accuracy 44 

Accuracy  in  thrust  from  the  shoulder  at  a  target approx.  60 

"          "  free  arm  drawing  of  a  line  within  an  angle 72 

Lowness  of  threshold  for  sensations  of  impact 43 

"         "         "           "           "           "  pain 46 

"         "         "           "           "           "  taste  (the  presence  of  a  taste) . .  34 

(recognition   of   it   as   sweet, 

salt,  sour  or  bitter) 34 

presence   and   recognition   of 

sweet  and  salt 45 

of  sour  and  bitter 22 

"         "         "           "           "           "  smell  (cloves  and  violet)  pres- 
ence    43 

recognition 41 

"  light 62 

Range  of  sensitivity  to  pitch;  upper  limit 52 

"      "           "          "       "       lower  limit 50 

Delicacy  of  discrimination  of  differences  in  pressure 47 

"  lifted  weights 66 

"  (points     on     the     forearm) 

crosswise 43 

lengthwise 18 

"  area  on  the  skin 61 

"  temperature  (at  30  C.) 53 

(at  5  C.) 36 

(at  45  C.) 52 

"  taste  (sweet  64,  salt  35,  sour 

67,  bitter  65) 58 

"  smell  (cloves  48,  violet  51).  50 

"  pitch 44 

"  brightness 78 

"  color  (as  in  tests  for  color- 
blindness)    24 

"         "             "               "          "           "  area  by  the  eye 56 

*Six  women  of  the  twenty-five  could  not  continue  so  long  as  the  most 
easily  fatigued  man.  Two  men  and  two  women  stopped  after  100  seconds. 
The  others  tapped  for  120  seconds. 


28 


Educational  Psychology 


Memory  of  nonsense  syllables;  rate  of  learning,  auditory 32 

"         "         "                "            "      "         "         visual 46 

Retentiveness  after  one  week;  auditory 51 

"                "       "        "       visual 43 

Quickness  in  solving  ingenuity  test  i 46 

"             "             "     2 60 

"    3 69 

"    4 68 

"    5 72 

General  information 50 

Information  about  English  literature 31 

"                "      physics 76 


Fig.  II.  The  amount  of  difference  between  two  groups  when  the  per 
cent  of  one  group  reaching  or  exceeding  the  median  of  the  other  group  is 
45  or  55. 


Fig.  12.  The  amount  of  difference  between  two  groups  when  the  per 
cent  of  one  group  reaching  or  exceeding  the  median  of  the  other  group  is 
40  or  60. 


Fig.  13.  The  amount  of  difference  between  two  groups  when  the  per 
cent  of  one  group  reaching  or  exceeding  the  median  of  the  other  group  is 
25  or  75. 


The  Influence  of  Sex 


29 


ta 


A  percent  of  100  is  ambiguous,  meaning  anything  from  the 
amount  of  difference  shown  in  Fig.  14  to  an  amount  as  great 
as  or  greater  than  that  shown  in  Fig.  15.    So  also  a  per  cent  of  o 


30  Educational  Psychology 

is  ambiguous,  meaning  possibly  a  difference  as  little  as  that  of 
Fig.  14  ^reversed),  and  possibly  a  difference  as  great  as  or 
greater  than  that  of  Fig.  15  (reversed). 

As  a  matter  of  fact  there  is  no  intellectual  ability  among  those 
so  far  measured  in  which  the  percentage  of  males  reaching  the 
median  for  females  is  as  low  as  o  or  as  high  as  100.  The  groups 
always  over-lap  to  the  extent  of  half  the  range  of  one  of  them, 
or,  more  exactly,  to  the  extent  of  the  distance  on  the  scale  from 
the  median  to  one  extreme  of  one  group. 

Wissler  ['01]  found,  in  the  case  of  young  men  and  women 
students  in  Columbia  University,  that  in  fatigue  at  pressing  a 
spring  with  thumb  and  forefinger,  in  the  perception  of  weight, 
and  in  discrimination  of  points  on  the  skin,  there  was  no  appreci- 
able superiority  of  either  sex.  Women  responded  with  the 
judgment  of  '  painful '  to  a  much  less  pressure  than  was  required 
in  the  case  of  men,  but  differences  in  the  standard  of  '  painful ' 
probably  played  a  large  part  in  the  effect.  Only  18  per  cent  of 
men  judged  painful  as  low  a  pressure  as  did  the  median  woman. 
Only  40  per  cent  of  men  were  as  accurate  in  judging  pitch  as 
was  the  median  woman,  but  in  the  case  of  size  the  figure  was 
75  per  cent.  In  quickness  of  reaction  time  to  sound  it  was  81, 
but  in  quickness  in  marking  out  A's  it  was  only  32  and  in  quick- 
ness in  naming  colors  it  was  only  18.  In  rate  of  movement 
about  60  per  cent  of  men  equaled  or  surpassed  the  median  woman, 
and  in  rate  of  association  (by  a  doubtful  test)  about  70.  In 
memory  there  was  a  trifling  female  superiority. 

Gilbert  ['94]  measured  100  boys  and  100  girls  of  each  age  from 
6  to  17,  chosen  at  random  from  those  in  school.  He  gives 
simply  the  medians  and  the  average  variations  of  the  individuals 
therefrom,  but  it  is  possible  to  estimate  from  his  data  very  closely 
the  percentages  of  boys  reaching  or  exceeding  the  median  for 
girls  in  the  case  of  the  traits  listed  below.  The  facts  are :  In 
the  case  of  boys  and  girls  8-14  years  old  (inclusive),  the  per  cent 
of  boys  reaching  or  exceeding  the  median  ability  for  girls  of  the 
same  age  is: — 

In  delicacy  of  sense-discrimination  for  weight 48 

In  delicacy  of  sense-discrimination  for  color  (shades  of  red) 39 

In  reaction  time 57 

In  resistance  to  the  size-weight  illusion 55 

In  rate  of  tapping 64 


The  Influence  of  Sex  31 

In  the  case  of  boys  and  girls  15-17  years  old  (inclusive),  the 
same  per  cent  is : — 

In  delicacy  of  sense-discrimination  for  weight 58 

In  delicacy  of  sense-discrimination  for  color  (shades  of  red) 58 

In  reaction  time 76 

In  resistance  to  the  size- weight  illusion 68 

In  rate  of  tapping 73 

I  have  compared  the  sexes  in  the  case  of  various  abilities,  shown 
in  objective  tests  and  in  school  marks,  with  the  results  shown  below. 
In  the  case  of  boys  and  girls  from  8-14  years  old  (inclusive)  the 
per  cent  of  boys  reaching  or  exceeding  the  median  ability  for  girls 
of  the  same  age  is : — 

In  tests  of  the  associative  and  conceptual  processes,  such  as  the 
opposites  test,  alphabet  test,  word  test,  addition  and  multi- 
plication        48 

In  speed  and  accuracy  in  noticing  small  details,  as  in  the 

A  test,  the  r-e,  o-n,  a-t  tests  and  the  like    33 

In  memory  of  words  for  a  few  seconds  (10-30) 40 

In  spelling 33 

In  the  case  of  boys  and  girls  of  the  same  classes  in  high 
schools  the  same  per  cent  is  : — 

In  tests  of  the  associative  and  conceptual  processes 50  (approx.) 

In  English     (Regents'  examination  and  school  mark) 41 

In  mathematics    "  "  "         "  "      57 

In  Latin  "  "  "         "  "      57 

In  history  "  "  "         "  "      60 

In  the  case  of  college  students  the  same  per  cent  is : — 

In  English 35  (approx.) 

In  mathematics 45  (approx.) 

History  and  economics 56  (approx.) 

Mental  Science 50  (approx.) 

Modern  languages 40  (approx.) 

In  the  case  of  college  students  the  selection  of  women  is 
narrower,  and  probably  a  little  better.  The  men  probably  devote 
less  time  to  their  college  studies.  The  students  in  question  were 
from  two  state  universities  in  the  north-central  states. 

The  most  important  characteristic  of  these  differences  is  their 
small  amount.  The  individual  differences  within  one  sex  so 
enormously  outweigh  the  differences  between  the  sexes  in  these 
intellectual  and  semi-intellectual  traits  that  for  practical  purposes 


32  Educational  Psychology 

the  sex  difference  may  be  disregarded.  So  far  as  ability  goes,  there 
could  hardly  be  a  stupider  way  to  get  two  groups  alike  within 
each  group  but  differing  between  the  groups  than  to  take  the 
two  sexes.  As  is  well  known,  the  experiments  of  the  past  generation 
in  educating  women  have  shown  their  equal  competence  in  school 
work  of  elementary,  secondary  and  collegiate  grade.  The  present 
generation's  experience  is  showing  the  same  fact  for  professional 
education  and  business  service.  The  psychologists'  measurements 
lead  to  the  conclusion  that  this  equality  of  achievement  comes 
from  an  equality  of  natural  gifts,  not  from  an  overstraining  of 
the  lesser  talents  of  women. 

In  detail  the  measurements  show  a  slight  inferiority  of  the  male 
sex  in  receptivity  or  impressibility  and  a  slight  superiority  in 
the  control  of  movement  and  in  thought  about  concrete  mechanical 
situations.  Dr.  Thompson  would  attribute  the  last  difference 
to  differences  in  training  and  a  charitable  male  psychologist 
might  so  attribute  the  superior  quickness  of  movement  also.  The 
matter  is  not  of  great  consequence,  first  because  the  differences 
themselves  are  not,  and  second  because  the  differences  in  training, 
if  they  exist,  are  probably  due  largely  to  original  differences 
between  the  interests  of  the  two  sexes.  If  boys  by  training  learn 
more  about  the  mechanical  properties  of  objects,  it  is  probably 
because  they  by  nature  care  more  about  such  learning.  It  can 
hardly  be  maintained  seriously  that  forced  differences  in  the 
training  of  these  50  students  in  the  University  of  Chicago  or  of 
boys  and  girls  in  New  Haven  and  New  York, — differences  in 
training,  that  is,  apart  from  the  selection  of  certain  training  by 
the  children's  natures, — favored  either  sex  in  such  a  matter  as 
solving  an  example  in  arithmetic  or  marking  out  A's  or  spelling 
or  giving  the  opposites  of  words. 

A  vast  amount  of  time  could  be  spent  in  analyses  of  the  minor 
differences  reported  and  in  argumentation  about  the  reasons  for 
them,  for  their  existence  in  original  nature  and  for  their  relations 
one  with  another.  It  would  be  largely  profitless,  however ;  for 
no  one  of  these  measurements  is  by  itself  very  reliable  and  their 
proper  use  is  only  to  decide  general  questions  about  large  differ- 
ences and  about  the  general  extent  to  which  sex  is  the  cause 
of  the  mental  variations  of  mankind.  They  suffice  to  prove  that 
the  sexes  are  closely  alike  and  that  sex  can  account  for  only 
a  very  small  fraction  of  human  mental  differences  in  the  abilities 


The  Influence  of  Sex  53 

listed.  They  do  not  suffice  to  prove  the  exact  nature  or  amount 
of  the  difference  in  each  special  trait. 

The  trivial  difference  between  the  central  tendency  of  men  and 
that  of  women  which  is  the  common  finding  of  psycholog-ical  tests 
and  school  experience  may  seem  at  variance  with  the  patent 
fact  that,  in  the  great  achievements  of  the  world  in  science,  art, 
invention  and  management,  women  have  been  far  excelled  by 
men.  One  who  accepts  the  equality  of  typical  (i.  e.,  modal) 
representatives  of  the  two  sexes  must  assume  the  burden  of 
explaining  this  great  difference  in  the  high  ranges  of  achievement. 

The  probably  true  explanation  is  to  be  sought  in  the  greater 
variability  within  the  male  sex.*  The  most  gifted  men  may  be 
superior  to  the  most  gifted  women  even  though  the  average 
man  is  equal  to  or  below  the  average  woman,  if  men  vary  zvidely 
enough  from  their  central  tendency.  Thus  in  Fig.  16  the  central 
tendencies  are  the  same  for  men  and  women,  but  there  are  two 
men  out  of  every  hundred  who  are  superior  to  all  women.  In 
Fig.  17  only  45  per  cent  of  men  reach  the  median  ability  for 
women,  but  i  of  the  45  is  superior  to  all  women. 

Sex  Differences  in  Variability 

A  difference  between  the  sexes  in  variability  may  be  of  as 
great  significance  as  a  difference  in  central  tendency.  This  will 
be  clearest  if  its  influence  is  observed  first  in  one  or  two  imagin- 
ary cases.  Suppose,  for  example,  that  the  average  position  of 
men  on  a  scale  for  morality  is  the  same  as  that  for  women, 
and  call  this  amount  of  morality  20  M.  Suppose  the  average 
deviation  of  individual  men  from  20  M  to  be  2  ]\I,  and  the 
average  deviation  of  women  from  20  M  to  be  3  M.  Then  the 
two  surfaces  of  frequency  would  probably  be  approximately  as 
in  Fig.    18.     The  best  man  would  be  about  twice  as  good  as 

*It  should  be  obvious  that  the  greater  variability  of  males  in  the  sense  of 
the  divergence  of  individuals  from  the  average  or  median  or  mode  of  their 
sex  implies  nothing  whatever  about  the  variability  of  individual  men  in 
the  sense  of  the  divergence  of  any  man's  different  'trials'  from  his  own 
general  average, — in  the  sense,  that  is,  of  the  inconstancy  of  performance 
of  an  individual.  Men  might  vary  widely  inter  se,  but  each  man  might  be 
a  very  constant  performer;  women  might  vary  very  little  from  the  modal 
woman,  yet  each  one  might  vary  enormously  on  different  occasions  from 
her  average  performance  or  central  tendency. 
3 


34 


Educational  Psychology 


the  worst  man,  all  men  being  between  about  12  M  and  28  M. 
The  limits  required  to  include  all  the  women  would,  on  the 
contrary,  range  from  about  8  M  to  32  M.    The  best  woman  would 


Fig.  i6.     The  continuous  line  encloses  the  surface  of  frequency  for  men ; 
the  dotted  line,  that  for  women. 


_  -I  I 
I  I 
I      I , 

I 

I 
I  I 

I 

I 

I 

I ' 

I 

I  — , 

I 

I 

I 

I 

I 
I 


ZL 


Fig.  17.     The  continuous  line  is  for  men;  the  broken  line,  for  women. 


be  four  times  as  good  as  the  worst.  About  two  women  out  of 
every  hundred  would  be  better  than  the  best  man ;  about  two 
would  be  worse  than  the  worst  man. 


The  Influence  of  Sex  35 

Thus,  though  the  average  morahty  would  be  the  same,  we 
would  have  differences  of  tremendous  practical  moment.  The 
great  acts  of  honor,  philanthropy,  nobility  and  sacrifice  would 
all  be  due  to  women.  At  the  same  time  they  would  commit 
all  the  basest  of  crimes  and  iniquities.  They  would  lead  in  all 
moral  endeavor,  but  would  also  fill  the  jails  and  dens  of  wicked- 
ness, while  the  men  would  present  lives  of  equable,  uninteresting 
mediocrity  of  both  vice  and  virtue.  If  the  reader  will  contemplate 
the  practical  importance  of  a  similar  difference  in  the  variability 
of  the  sexes  in  intelligence,  originality,  musical  talent,  piety  and 


VM.  8M.  I2M  20M.  iSM.  32^rt. 

Fig.  18.     The  status  of  men  and  women,  the  two  central  tendencies  being 
identical,  if  the  men  vary  only  two-thirds  as  much  as  the  women. 


Other  traits,  he  will  see  that  its  measurement  is  in  no  wise  a 
matter  of  merely  abstract  interest. 

In  particular,  if  men  differ  in  intelligence  and  energy  by  wider 
extremes  than  do  women,  eminence  in  and  leadership  of  the 
world's  affairs  of  whatever  sort  will  inevitably  belong  oftener 
to  men.  They  will  oftener  deserve  it.  But  the  greater  male 
variability  should  result  also  in  a  great  preponderance  of  men 
amongst  the  most  idiotic  idiots.  Just  this  seems  to  be  the  case. 
Cattell  says  ['03,  p.  375]  in  the  course  of  his  report  on  the 
thousand  most  noted  individuals  of  the  civilized  world: — 

"  I  have  spoken  throughout  of  eminent  men  as  we  lack  in 
English  words  including  both  men  and  women,  but  as  a  matter 
of  fact  women  do  not  have  an  important  place  on  the  list.  They 
have  in  all  32  representatives  in  the  thousand.  Of  these  eleven 
are  hereditary  sovereigns  and  eight  are  eminent  through  mis- 


36  Educational  Psychology 

fortunes,  beauty  or  other  circumstances.  Belleslettres  and  fiction 
— the  only  department  in  which  woman  has  accompHshed  much — 
give  ten  names  (of  which  three  are  in  the  first  500)  as  compared 
with  72  men.  Sappho  and  Joan  d'Arc  are  the  only  other  women 
on  the  list.  It  is  noticeable  that  with  the  exception  of  Sappho — 
a  name  associated  with  certain  fine  fragments — women  have  not 
excelled  in  poetry  or  art.  Yet  these  are  the  departments  least 
dependent  on  environment  and  at  the  same  time  those  in  which 
the  environment  has  been  perhaps  as  favorable  for  women  as  for 
men.  Women  depart  less  from  the  normal  than  man — a  fact  that 
usually  holds  for  the  female  throughout  the  animal  series  ;  in  many 
closely  related  species  only  the  males  can  be  readily  distinguished. 
The  distribution  of  women  is  represented  by  a  narrower  bell- 
shaped  curve." 

In  a  study  restricted  to  British  genius  Ellis  ['04,  p.  lo-ii]  finds 
a  similar  failure  of  women  to  reach  the  extreme  of  men. 

"In  the  final  result  my  selection  yields  975  British  men  of  a 
high  degree  of  intellectual  eminence.  The  eminent  women  num- 
ber 55,  being  in  proportion  to  the  men  about  i  to  18. 

A  slightly  lower  standard  of  ability,  it  would  appear,  prevails 
among  the  women  than  among  the  men.  On  account  of  the 
greater  rarity  of  intellectual  ability  in  women,  they  have  often 
played  a  large  part  in  the  world  on  the  strength  of  achievements 
which  would  not  have  allowed  a  man  to  play  a  similarly  large 
part.  It  seemed,  again,  impossible  to  exclude  various  women  of 
powerful  and  influential  personality,  though  their  achievements 
were  not  always  considerable.  I  allude  to  such  persons  as 
Hannah  More  and  Mrs.  Montague.  Even  Mrs.  SomerviUe,  the 
only  feminine  representative  of  science  in  my  list,  could  scarcely 
be  included  were  she  not  a  woman,  for  she  was  little  more  than 
the  accomplished  popularizer  of  scientific  results.  In  one  depart- 
ment, and  one  only,  the  women  seem  to  be  little,  if  at  all,  inferior 
to  the  men  in  ability,  that  is  in  acting." 

It  is  well  known  that  very  marked  intellectual  weakness  is 
commoner  amongst  men  than  amongst  women.  Two  times  as 
many  men  as  women  will  be  found  in  asylums  for  idiots  and 
imbeciles ;  and  one  and  a  third  times  as  many  will  be  found  by 
a  census  including  those  cases  (commonly  somewhat  less  stupid) 
cared  for  at  home. 

In  the  case  of  general  ability  both  extremes  of  both  sexes  are 


The  Influence  of  Sex  37 

thus  fairly  measured  for  us,  but  in  more  specialized  traits  care- 
ful measurements  are  needed  of  the  comparative  variability  of 
men  from  the  typical  or  '  modal '  man  and  of  woman  from  the 
'  modal '  woman. 

Methods  of  Comparing  the  Sexes  in  Respect  to  Variability 

When  the  two  groups  are  equal  in  respect  to  their  central 
tendencies  it  is  easy  to  compare  their  variabilities.  For  instance, 
in  the  case  of  the  pressure  required  to  cause  a  judgment  of 
"  painful "  the  results  in  Dr.  Thompson's  investigation  ['03] 
were  that  the  pressure  required  ranged  from  800  to  3600  grams 
for  women  and  from  800  to  4000  for  men.  The  average  deviation 
of  the  25  pressures  required  for  the  25  men  from  that  required 
for  the  average  or  median  man  was  about  960  grams,  while  that 
in  the  case  of  women  was  only  about  530  grams.  Twenty  of 
the  twenty-five  women  are  included  within  a  range  of  1600 
grams,  but  a  range  of  over  2800  grams  is  required  to  include 
twenty  of  the  twenty-five  men.  If  the  men  and  women  were 
alike  in  their  central  tendencies  no  objection  could  be  raised  to 
comparing  their  variabilities  by  the  above  figures. 

But  if  the  men  were  markedly  less  sensitive  to  pain — if  the 
pressure  required  ranged,  for  them,  from  4000  to  8000,  but  for 
women  from  800  to  3600 — if  the  median  man  required  6000 
whereas  the  median  woman  required  only  2200, — then  the  greater 
range  or  greater  average  deviation  of  men  might  not  mean  a 
greater  real  variability.  For,  an  objector  could  properly  say, 
the  average  deviation  of  butterflies  from  their  average  in  weight 
is  only  a  small  fraction  of  an  ounce  whereas  the  average  deviation 
of  men  from  their  average  is  a  hundred  or  more  ounces,  yet 
butterflies  really  vary  more  in  weight  than  men  do.  Only  if  one 
man  weighs  twice  as  much  as  another  and  if  one  butterfly  weighs 
twice  as  much  as  another  may  the  variations  be  called  equal  in 
the  two  cases,  the  objector  may  continue.  Equal  variability  should  I 
mean  equal  ratios,  not  equal  amounts.  ' 

There  is  obviously  much  force  in  this  objection,  and  in  the 
recommendation  that  a  variability  around  a  C.  T.*  of  20  must  be 
two  times  as  large  as  a  variability  around  a  C.  T.  of  10  to  be 
properly  called  equal  to  it.     In  certain  cases,  in  fact,  this  method 

*I  shall  use  C.  T.  as  an  abbreviation  for  Central  Tendency. 


C.  T. 

9 

C.  T. 

i6 

C.  T. 

24 

38  Educational  Psychology 

is  demonstrably  just.  The  absolute  or  gross  variation  of  sermons 
in  length  would  be  much  greater  than  the  gross  variation 
in  the  length  of  the  sentences  composing  them,  but  really  the 
latter  are  much  more  variable.  Again,  22  individuals  worked 
addition  examples,  first  for  forty,  then  for  eighty,  then  for  one 
hundred  and  twenty  seconds.     The  scores  were,  respectively: — 

A.  D.*  2.18 
A.  D.  3.41 
A.  D.     5.18 

Now  the  real  variability  of  these  22  individuals  in  addition  is 

substantially  the  same  thing  in  all  three  tests.    They  were  not  two 

and  a  half  times  as  much  unlike  among  themselves  in  the  third 

test  as  in  the  first!    An  Average  Deviation  of  2.18  around  a  C.  T. 

of  9  measures  the  same  fact  as  an  Average  Deviation  of  5.18 

around   a   C.  T.   of  24.        If,   instead  of   the  gross  variabilities 

(2.18,      3.41  and  5.18),  we  use  their  ratios  to  the  C.T.s  (/.  e., 

2.18        3.41         ,  5.i8-  J         \    .1  • 

'       — ^^'  and '    or   .24,       .21    and    .22)    this   sameness 

9  16  24 

in  reality  is  paralleled  by  the  measures.  If  women  tested  in 
addition  for  80  seconds  showed  a  C.  T.  of  16  and  an  A.  D.  of 
3.4,  while  men  tested  for  120  seconds  showed  a  C.  T.  of  24 
and  an  A.  D.  of  5.1,  it  would  certainly  be  absurd  to  claim  there- 
from that  men  were  one  and  a  half  times  as  variable  as  women. 

On  the  other  hand,  it  would  be  folly  to  assume  that  the  ratios 
of  the  gross  variabilities  to  the  corresponding  C.  T.s  are 
infallibly  fair  bases  for  comparing  the  real  variabilities  of  groups. 
For  instance,  tall  men  vary  actually  less  among  themselves  in 
stature  than  do  short  men.  So  also  men  with  long  middle 
fingers  vary  actually  less  in  the  length  of  their  middle  fingers 
than  do  men  with  short  middle  fingers. 

As  a  matter  of  theory  the  allowance  to  be  made  for  a  difference 
in  central  tendency,  when  groups  are  compared  in  variability 
in  a  mental  trait,  should  be  that  obtained  by  dividing  each  gross 
variability  by  the  square  root  of  the  central  tendency  rather 
than  that  obtained  by  dividing  through  by  the  central  tendency 
itself.  In  anatomical  measurements  empirical  facts  support  this 
theoretical  expectation. 

In  measurements  by  scales  with  arbitrary  units,  such  as  school 

*  A.  D.  stands  for  Average,  or  Mean,  Deviation. 


The  Inflncnce  of  Sex 


39 


marks,  any  comparison  of  groups  in  respect  to  variability  is 
treacherous  if  the  groups  differ  in  central  tendency.  Thus  suppose 
men  and  women  to  receives  grades  in  history  as  follows : — 


Grades  40-44  were  given  to    o  men  and  to 


45-49 
50-54 

55-59 
60-64 
65-69 
70-74 

75-79 
80-84 
85-89 
90-94 
95-99 


o 
o 

4 
10 

23 
61 

75 
61 

23 
10 

4 


to      4 

wom.en 

"    10 

"    ^Z 

"    61 

"    75 

"    61 

"    23 

"    10 

"      4 

The  Average  Deviation  for  men  and  that  for  women  are  equal. 
The  C.  T.s  are  62  (60-64)  for  women  and  jy  (75-79)  for  men. 
The  best  women  get  marks  about  twice  as  high  as  the  worst 
women,  whereas  the  best  men  get  marks  about  one  and  three- 
fourths  times  as  high  as  the  worst  men.  But  the  variability 
of  men  may  be  really  greater  than  that  of  women.  For  the 
difference  called  i  from  85  to  99  may  be  very  much  greater  than 
the  difference  called  i  from  40  to  54.  Moreover  the  fact  that 
the  best  woman  gets  marks  two  times  as  high  as  the  worst  woman 
tells  nothing  about  how  many  times  as  much  she  knows  or  how 
many  times  as  well  she  can  do.  The  'times  '  statement  is  justifiable 
only  when  the  o  of  the  scale  means  absolute  nothingness  of  the  trait 
in  question.  80  is  twice  40,  84  is  twice  42  only  if  it  is  twice  as 
far  from  the  dividing  point  between  nothing  and  just  barely 
something  on  the  scale  for  the  trait  in  question. 

In  any  one  mental  trait  the  comparison  of  men  and  women 
in  variability  may  thus  be  ambiguous,  but  since  the  central 
tendency  for  males  is  below  about  as  often  as  above  that  for 
females,  the  possibility  of  error  tends  in  the  long  run  almost  equally 
toward  exaggeration  and  toward  unfair  diminution  of  male  vari- 
ability. So  in  a  score  or  more  of  traits  taken  at  random  in  respect 
to  this  question,  any  fundamental  difference  between  the  sexes  in 
variability  should  be  fairly  measured. 


40  Educational  Psychology 

The  Results  of  Measurements  of  Sex  Differences  in  Variability 

It  is  unfortunate  that  so  little  information  is  available  for  a 
study  of  sex  differences  in  the  variability  of  mental  traits  in  the 
case  of  individuals  over  fifteen.  Such  statistics  as  I  have  been 
able  to  secure  give  measures  in  26  objective  tests,  with  from 
100  to  1,500  individuals,  and  in  25  records  of  school  marks  with 
from  60  to  1,000  individuals. 

The  comparisons  in  the  case  of  reaction  time,  reaction  time 
with  discrimination  and  choice,  and  time  memory  are  based  on 
the  measurements  given  by  Gilbert  ['94].  For  the  data  in 
spelling,  arithmetic  and  in  the  r-e  and  o-n  tests  I  am  indebted 
in  part  to  Messrs.  E.  L.  Earle,  W.  A.  Fox  and  L.  W.  Cole. 

The  nature  of  the  material,  which  represents  measurements 
taken  by  different  individuals  and  often  with  only  small  groups, 
makes  inferences  from  details  unreliable.  The  data  would  be 
slightly  more  accurate  if  all  records  had  been  reduced  to  a 
common  month  age  at  least,  but  this  could  not  be  done  with 
the  measurements  taken  by  other  observers  than  myself  and 
would  involve  an  amount  of  labor  out  of  proportion  to  the 
increase  in  accuracy.  The  main  facts  that  are  relevant  to  our 
present  purpose  are  as  follows :  Variability  being  measured  by 
the  per  cent  which  the  gross  variability  is  of  the  central  tendency, 
the  sexes  differ  as  shown  in  Table  5. 

If  the  gross  variabilities  themselves  are  used,  the  ratios  for 
the  A  test,  a-t  test,  word  test,  memory  of  words  and  spelling  are 
somewhat  higher,  those  for  discrimination  and  reaction  time  are 
somewhat  lower,  while  those  for  the  opposites  test,  time  memory, 
addition,  multiplication,  and  scholarship  remain  practically  the 
same.  The  general  effect  would  be  to  raise  the  ratios  somewhat 
since  in  the  particular  tests  given  the  central  tendency  for  girls 
is  more  often  above  than  below  that  for  boys. 

These  facts  make  it  extremely  probable  that,  except  in  the  two 
years  nearest  the  age  of  puberty  for  girls,*  the  male  sex  is 
slightly  more  variable.  From  the  time  of  puberty  for  boys  to 
maturity  this  difference  seems  to  increase  rapidly,  though  the 
records  of  marks  which  support  this  conclusion  are  not  the  best 
of  evidence. 

The  variability  of  girls  with  respect  to  the  age  at  which  any 

*The  greater  variability  of  girls  in  these  two  years  is  probably  a  result 
of  sex  difference  in  the  rate  of  mental  growth. 


The  Influence  of  Sex  41 

TABLE  5. 

Ratio  of  Female  to  Male  Variability. 

By  ages.  9  10  11  12  13  14       15       16        17 

A  test 86  I. II  1.04  .94  1.08  1.03    1.07 

A-t  test 91  1.05  1.05  1.07  1.35  1.07      .73 

Easy  opposites  test .97  .81  i.io  1.24      .89    1.15 

Word  test 1.05  .91  .85      .87 

Memory  (related  words) ..  .    .77  .137  .93  .72 

Memory  (unrelated  words) .    .77      .46  .94  .66  .77  1.28 

Discrimination  of  length. .  .     .75      .80  .81  .98  1.04      .70      .78 
Simple   and   discriminative 

reaction  time 98  1.21  .98  .93  i.oo  i.ii      .83    1.14    1.22 

Time  memory 56      .75  1.21      .82  .85  1.27    1.26      .66    1.06 

General  ratio.     Average...  .92  1025  .97 

Median....  .93  1.035  -95 

The  chances  are  i  to  i  that  the  true  result  will  not  vary  from  the  one 
obtained  by  more  than  .023  (9-12  yrs.),  .04  (13-14  yrs.),  .055  (15  yrs.). 

By  grades.  45678     isthigh. 

R-e  and  o-n  tests 77  1.19  .97  .82  .85 

Spelling 55  .69  .55  .68  .68 

Addition i.oo  .91  1.06  .85  .97 

Multiplication .56  1.15 

In  a  number  of  tests  (six  in  all)  the  ratio  of  first-year  high  school  girls 
to  boys  in  variability  was  .975. 

In  tests  in  arithmetic  (six  in  all)  the  ratio  of  high  school  girls  to  boys 
in  variability  was  .96;  in  regents'  examinations  in  Latin,  English  and  in 
history,  it  was  .96;  in  school  marks  in  eight  subjects,  it  was  on  the  average  .86. 

In  college  marks  in  fourteen  different  courses  the  ratios  averaged  .85. 

given  school  grade  is  reached  is  less  than  that  of  boys.  The 
difference  is  not  necessarily  attributable  in  its  entirety  to  an  original 
difference  between  the  natures  of  boys  and  girls.  The  greater 
variations  of  boys  toward  high  ages  in  particular  are  probably 
due  in  part  to  the  slower  maturing  of  boys,  to  the  greater 
frequency  of  temporary  withdrawal  and  to  other  factors  irrespec- 
tive of  an  original  greater  variability.  But  in  so  far  as  boys 
are  found  both  younger  and  older  than  girls  at  entrance  to  a 
grade,  the  evidence  of  their  greater  variability  in  the  complex  of 
abilities  that  determines  rate  of  progress  in  school  is  sound.  A 
careful  estimate  will  probably  show  that  in  this  complex  girls 
are  not  over  95  per  cent  as  variable  as  boys. 

For  instance  the  combined  figures  for  the  census  of  the  third- 


20  and  over. 

Total 

17 

975 

10 

974 

42  Educational  Psychology 

year   high   school    classes    (1908)    in    Detroit,   Fall    River,    Los 
Angeles,  Lowell  and  Worcester  were : — * 

Age     13     14      15      16      17      18      19      20  and  over.     Total 
Boys     3     18    113    237    274    154      69     25  893 

Girls      I      12    104    298    265    177      40      10  907 

In  Chicago  (1908)  the  figures  were  (the  numbers  for  the  1164 
girls  being  reduced  to  a  basis  of  975)  : — 

Age  13     14     15     16     17     18     19 

Boys  I     34  165  306  291   127     34 

Girls  I     13  127  371  288  132     32 

In  Philadelphia  (1908)  the  figures  were  (the  numbers  for  the 
872  boys  being  reduced  to  a  basis  of  750)  : — 

Age  13     14     15     16     17     18     19     20  and  over.     Total 

Boys  I       3     42  223  256  168     47     10  750 

Girls  31  292  282  III     28       6  750 

In  New  York  (1905.  Report  of  Superintendent  of  Schools, 
p.  72)  the  figures  were  (the  numbers  for  the  1939  girls  being 
reduced  to  a  basis  of  1356)  : — 

Age     13     14     15     16     17     18     19     20     21  and  over.  Total 
Boys     2     37  274  480  382  123     43     12       3  1356 

Girls     2     48  300  390  454  134     20       3       5  1356 

On  the  whole  boys  are  twice  as  frequent  as  girls  in  the  youngest 
and  oldest  age  groups  and  about  one  and  one-half  times  as 
frequent  at  ages  14  and  19. 

Dr.  Thompson  does  not  calculate  the  variability  within  either 
sex,  nor  present  the  facts  on  sufficiently  fine  scales  to  allow  anyone 
else  to  do  it  exactly.  I  have  calculated  it  as  well  as  may  be 
from  the  measurements  which  she  gives,  with  the  result  that 
the  variability  among  the  25  women  seems  on  the  whole  only 
93  per  cent  of  that  of  the  men.  The  difference  is  closely  the 
same  whether  the  gross  variabilities  are  used  directly  or  are 
first  divided  by  the  corresponding  central  tendencies  or  by  the 
square  roots  of  the  latter.  In  reaction  time,  in  the  rate  of 
sorting  colors,  and  in  memory  the  25  women  are  more  variable  ; 
in  accuracy  in  hitting  a  target,  in  sensory  discrimination  and  in 

*For  the  statistics  from  which  these  measurements  are  computed  I  am 
indebted  to  the  U.  S.  Bureau  of  Education,  through  Prof.  G.  D.  Strayer. 


The  Influence  of  Sex  43 

the  tests  of  ingenuity  they  are  almost  or  quite  as  variable.  But 
in  the  majority  of  tests  they  are  less  variable.  On  the  whole 
the  most  probably  true  estimate  is  that  women  are  one  twentieth 
less  variable  than  men. 

Wissler's  results  [01]  with  college  students  show  female  vari- 
ability to  be  in  general  about  nine-tenths  that  of  males.  The 
number  of  women  measured  was,  however,  only  42,  and  the 
ratio  of  female  to  male  variability  differed  greatly  in  the  different 
traits,  so  that  the  nine-tenths  would,  by  itself  alone,  be  of  no 
great   reHability. 

Sex  Differences  in  Traits  Not  Measured  Objectively 

We  have  now  to  turn  from  fairly  satisfactory  studies  of  sex 
differences  in  sensory,  motor  and  intellectual  capacities,  to  a  looser 
discussion  of  the  life  of  feeling,  action  and  general  achievement. 
Here  objective  and  precise  measurements  will  seldom  be  at  our 
service. 

There  are  two  studies  which  do  report  such  dift'erences 
quantitatively,  but  the  data  given  are  subject,  unfortunately,  to 
whatever  errors  of  prejudice  or  custom  teachers,  physicians,  and 
German  women  of  intellectual  interests  make  in  rating  individuals, 
and  to  possibly  important  errors  due  to  the  existence  in  their 
minds  of  different  standards  for  the  two  sexes. 

Karl  Pearson  ['04],  in  securing  data  on  the  resemblances  of 
children  of  the  same  parents,  had  children  rated  by  their  teachers 
for  various  qualities — as  quiet  or  noisy,  shy  or  self-assertive, 
and  the  like.  The  results  in  the  case  where  a  boy  and  his  sister 
were  both  rated  are  given  in  Table  6.  If  taken  at  their  face 
value  they  show  boys  to  be  somewhat  more  athletic,  noisier, 
more  self-assertive,  more  self-conscious,  less  popular,  duller  in 
conscience,  quicker-tempered,  less  sullen,  a  little  duller  intel- 
lectually, and  less  efficient  in  penmanship,  in  the  exact  degrees 
given  by  Table  6. 

They  cannot  be  thus  taken  unreservedly  ;  for,  even  in  comparing 
individuals,  opinions  about  the  sexes  as  total  groups  might  be 
influential  and  taint  the  estimates  with  some  measure  of  current 
irrational  prejudices.  This  error  would  probably  increase 
differences  beyond  their  real  amounts.  Such  prejudices,  if  exist- 
ing, would  work  still  more  insidiously  in  placing  the  dividing  line 
between  say  keenness  and  dullness  of  conscience  at  a  different 


44  Educational  Psychology 

point  in  the  case  of  boys  than  was  assigned  to  it  in  the  case  of 
girls.  A  boy  may  not  have  to  be  really  as  conscientious  or  may 
have  to  be  really  more  athletic  in  order  to  be  regarded  by  current 
standards  as  equally  conscientious  or  equally  athletic  in  comparison 
with  his  sister.  This  error  would  result  in  reducing  differences 
below  their  real  amounts.  However,  these  measurements  are 
much  preferable  to  general  announcements  of  opinion  concerning 
boys  and  girls,   unless   made  by   specially  competent  observers. 

TABLE  6. 
Ratings  by  Teachers  of  Boys  and  their  Sisters  in  Respect  to  Various 

Traits. 


Boys 

Girls 

Athletic 

291 

243 

Betwixt 

12 

9 

Non-athletic 

131 

182 

Quiet 

440 

525 

Noisy- 

313 

228 

Shy 

312 

355 

Self-assertive 

262 

218 

Self-conscious 

380 

337 

Unself-conscious 

277 

321 

Popular 

474 

487 

Unpopular 

81 

67 

Conscientiousness 

Keen 

427 

490 

Dull 

260 

197 

Temper 

Quick 

142 

116 

Good-ntaured 

490 

501 

Sullen 

72 

88 

Ability 

Quick-intelligent 

131 

129 

Intelligent 

271 

302 

Slow-intelligent 

280 

273 

Slow 

106 

no 

Slow-dull 

49 

31 

Very  dull 

23 

16 

Handwriting 

Very  good 

51 

38 

Good 

249 

313 

Moderate 

300 

274 

Poor 

III 

90 

Bad 

15 

II 

Very  bad 

3 

2 

^  The  Influence  of  Sex 


45 


The  greater  variability  found  for  males  (see  Table  6  under 
Ability  and  Handwriting)  is  a  sign  of  the  trustworthiness  of  the 
data ;  and  the  direction  of  the  differences  in  no  case  contradicts 
what  little  objective  evidence  exists.  So  the  amounts  of  differ- 
ence are  worthy  of  acceptance  until  a  more  adequate  study  is 
made.  They  are  slight ;  there  is  much  overlapping  of  one  sex 
by  the  other  and  a  far  greater  range  of  difference  within  either 
sex  than  between  the  averages  of  the  two. 

On  calculating  the  probable  percentages  of  boys  reaching  or 
exceeding  the  degree  of  each  trait  that  is  reached  or  exceeded  by 
half  of  the  girls,  we  have : — 

than  the  median  girl. 


6i%  of  boys  are  as  athletic           as  or  more  athletic           th 

62%       • 

'             "     noisy                        " 

noisy 

42%       ' 

"     shy                            " 

shy 

57%       ' 

'             "     self-conscious         " 

self-conscious 

46%       ' 

'             "     popular                   " 

popular 

40%       ' 

'             "     conscientious          " 

conscientious 

56%       ' 

'             "     quick-tempered      " 

quick-tempered 

47%       ' 

'             "     intelligent                " 

intelligent 

43% 


write  as  well  as  or  better  than  the  median  girl. 


Heymans  and  Wiersma  ['06,  '07  and  '08]  studied  mental  differ- 
ences of  the  sexes  by  means  of  estimates  of  individuals  made 
by  other  individuals  who  knew  them  more  or  less  intimately.  The 
report  covered  90  topics,  some  of  which  included  several  traits. 
The  individual  was  graded  very  coarsely — e.  g.,  as  emotional  or 
not  emotional ;  or  as  a  drunkard,  an  habitual  drinker,  an  occasional 
drinker,  or  a  total  abstainer.  Such  reports  are,  as  has  been  noted, 
inferior  evidence,  since  the  person  making  them  may  use  different 
standards  for  men  and  for  women.  Thus  the  same  degree  of 
emotionality  might  be  called  emotional  in  the  case  of  a  man  and 
not  emotional  in  the  case  of  a  woman,  or  vice  versa.  IVIoreover 
when,  as  often  happens,  no  rating  at  all  is  given  in  a  trait,  it 
may  be  because  the  condition  of  the  individual  to  be  rated  was 
not  known  in  the  case  of  that  trait,  or  because  he  was  on  the 
dividing  line  between  the  two  classes  (or  in  the  case  of  a  single 
judgment,  like,  "Has  he  mathematical  talent?"  lacked  the  specified 
degree  of  the  quality).  Finally,  general  superstitions  about  sex 
differences  may  affect  the  ratings  of  individuals.  In  the  case  of 
the  ratings  given  by  women  it  seems  probable  that  some  of  the 
women  knew  that  their  ratings  were  to  be  used  for  a  study  of 


46  Educational  Psychology 

sex  differences.  In  the  case  of  the  ratings  given  by  men  this 
was  apparently  not  so  often  the  case. 

On  the  whole,  the  results  of  the  ratings,  though  very  inferior 
to  objective  measurements,  are  probably  superior  to  the  mere 
opinions  which  one  could  give  from  reflection  on  the  common 
facts  of  life  and  his  own  narrow  circle  of  acquaintances.  They 
may  at  least  serve  to  make  the  reader  critical  of  whatever  such 
opinions  he  has. 

The  authors  do  not  pretend  to  distinguish,  in  the  case  of  any  of 
these  traits,  the  differences  due  to  sex  itself  and  the  differences 
due  to  the  difference  in  the  training  given  to  girls.  They  do, 
however,  give  interesting  statements  of  the  difference  between 
the  present  and  the  previous  generation. 

Their  own  conclusions  are  that  the  fundamental  differences 
shown  by  their  studies  are  the  greater  (i)  activity,  (2)  emotion- 
ality, and  (3)  unselfishness  of  the  female.  They  consider  women 
to  be  more  impulsive,  less  efficient  intellectually,  and  more  fickle 
than  men  as  a  result  of  the  first  two  differences  mentioned  above ; 
to  be  more  gifted  in  music,  acting,  conversation  and  the  invention 
of  stories  as  a  result  in  part  of  the  second  difference ;  and  to 
think  well  of  people  and  be  easily  reconciled  to  them  as  a  result 
of  the  third  ['07  p.  20]. 

These  conclusions  are  vague  and  the  tables  of  comparison  of 
the  sexes  which  give  rise  to  them  are  exceedingly  long  and 
obscure.    The  latter  take  the  form  of  90  classifications  such  as : — 

From  the  reports  made  From  the  reports  made 

almost  exclusively  by  almost  exclusively  by 

men,  the  per  cents  of  women,  the  per  cents 

men  and  of  women  were :  were : 

Emotional 

Not  emotional 


Men 

Women 

45 

60 

40 

27 

len 

Women 

49 

71 

40 

20 

I  have  therefore  calculated  from  them  the  probable  per  cent 
of  men  reaching  or  exceeding  the  median  woman  in  respect  to 
each  trait,  counting  the  ratings  by  men  and  those  by  women  as 
of  equal  weight.  The  differences  so  estimated  I  have  arranged 
roughly  in  the  order  of  their  magnitude.  The  largest  difference  is 
that  :— 

Only  15  per  cent  of  men  are  as  much  more  interested  in  persons  than  in 
things  as  the  median  woman  is. 


The  Influence  of  Sex 


47 


The  next  largest  differences  are  that : — 

In  accurate  and  orderly  reten- 
tion of  what  is  read 73%  of  tnen  equal  or  excel  the  median  woman. 

In  industry 28% 

In  adroitness  in  manual  work  28% 

In  love  of  sedentary  games  of 
skill 71% 

In  emotionality 30% 

In  temperance  in  the  use  of 
alcoholic  drinks  .  .  .  30%  (or  less) 

In  independence 70% 

In  zeal  for  money  making .  .  .  69% 

In  desire  for  change 32% 

In  impulsiveness 34% 

In  quickness  of  recovery  from 
grief 66%"      "        "      " 

Then  come  the  following : 

In   activity    (of   the   aimless 

sort) 36%  of  men  equal  or  excel  the  median  woman. 

In  dissatisfaction  with  oneself  36% 

In  religiousness 36% 

In  excitabiHty 37% 

In  sympathy 38% 

In  patience 38% 

In  love  of  sports 62% 

In  humor 61% 

In  risibility 39% 

In  talkativeness 40% 

In  gaiety 40% 

In  vanity  of  person 40% 

There  are  very  slight  differences  as  follows :  men  are  a  little 
oftener  reported  as  critical,  attached  to  opinions  once  formed, 
given  to  ambitious  plans,  given  to  contradiction,  sensible,  decisive, 
gifted  in  mathematics,  gifted  in  literature,  specific,  of  good 
memories,  fond  of  eating  and  drinking,  fond  of  distinction,  strict, 
and  also  easy-going,  in  discipline  with  children,  kind  to  sub- 
ordinates, widely  read,  and  punctual.  They  are  a  little  less 
often  reported  as  good-natured,  anxious,  easily  reconciled  after 
anger,  insistent  on  immediate  results,  good  judges  of  human 
nature,  practically  resourceful,  narrow,  gifted  in  languages, 
gifted  in  music,  good  observers,  thrifty,  domineering,  kind  and 
careful  in  discipline  with  children,  active  in  philanthropic  work, 
demonstrative,  honest  about  money,  fond  of  intercourse  with  social 


48  Educational  Psychology 

superiors,  timid,  well  posted  about  the  affairs  of  acquaintances, 
polite,  attentive,  tidy,  and  courageous  in  sickness. 

In  the  following  traits  there  is  still  less  difference  reported  or 
no  difference  observable :  Trustfulness,  tolerance,  inconstancy  in 
sympathies,  devotion  to  old  memories,  quickness  in  comprehension, 
superficiality,  stupidity,  ability  in  drawing,  acting,  mimicing,  ear 
for  music,  patriotism,  naturalness,  straightforwardness,  truthful- 
ness, kindness  to  animals,  snobbishness,  courage,  and  pleasure- 
seeking. 

It  is  not  desirable  to  comment  further  on  these  results  of 
Heymans'  and  Wiersma's  work,  until  further  study  by  more 
objective  methods  has  been  given  to  the  topic. 

It  would  be  desirable  in  any  such  study  that  the  sex  differ- 
ences in  the  instinctive  acts,  interests,  aversions  and  em.otional 
responses  should  be  studied  apart  from  the  differences  in  similar 
traits  that  have  been  produced  by  circumstances.  Two  instincts 
are  worthy  of  special  attention.  The  most  striking  difference  in 
instinctive  equipment  consists  in  the  strength  of  the  fighting 
instinct  in  the  male  and  of  the  nursing  instinct  in  the  female. 
No  one  will  doubt  that  men  are  more  possessed  by  the  instinct 
to  fight,  to  be  the  winner  in  games  and  serious  contests,  than 
are  women ;  nor  that  women  are  more  possessed  than  men  by 
the  instinct  to  nurse,  to  care  for  and  fuss  over  others,  to  relieve, 
comfort  and  console.  And  probably  no  serious  student  of  human 
nature  will  doubt  that  these  are  matters  of  original  nature.  The 
out  and  out  physical  fighting  for  the  sake  of  combat  is  pre- 
eminently a  male  instinct  and  the  resentment  at  mastery,  the 
zeal  to  surpass  and  the  general  joy  at  activity  in  mental  as  well 
as  physical  matters  seem  to  be  closely  correlated  with  it.  It  has 
been  common  to  talk  of  women's  "dependence."  This  is,  I  am 
sure,  only  an  awkward  name  for  less  resentment  at  mastery.  The 
actual  nursing  of  the  young  seems  likewise  to  involve  equally 
unreasoning  tendencies  to  pet,  coddle,  and  "do  for"  others.  The 
existence  of  these  two  instincts  has  been  long  recognized  by 
literature  and  common  knowledge,  but  their  importance  in  causing 
differences  in  the  general  activities  of  the  sexes  has  not.  The 
fighting  instinct  is  in  fact  the  cause  of  a  very  large  amount  of 
the  world's  intellectual  endeavor.  The  financier  does  not  think 
merely  for  money  nor  the  scientist  for  truth  nor  the  theologian 
to    save    souls.      Their    intellectual    efforts    are    aimed    in    great 


The  Influence  of  Sex  49 

measure  to  outdo  the  other  man,  to  subdue  nature,  to  conquer 
assent.  The  maternal  instinct  in  its  turn  is  the  chief  source  of 
woman's  superiorities  in  the  moral  life.  The  virtues  in  which 
she  excels  are  not  so  much  due  to  either  any  general  moral 
superiority  or  any  set  of  special  moral  talents  as  to  her  original 
impulses  to  relieve,  comfort  and  console. 

Training  undoubtedly  accentuates  these  inborn  differences 
since  boys  play  more  with  boys  and  are  trained  more  by  men,  the 
opposite  holding  with  girls.  A  reversal  of  training  by  which 
girls  would  be  surrounded  by  the  social  milieu  now  affecting 
boys  would,  as  we  often  see  in  isolated  cases^  lessen  the  sex 
difference.  But  we  may  be  sure  that  if  we  should  keep  the 
environment  of  boys  and  girls  absolutely  similar  these  instincts 
would  produce  sure  and  important  differences  between  the  mental 
and  moral  activities  of  boys  and  girls. 

Since  these  differences  in  instinctive  equipment  are  true  causes 
it  seems  wise  not  to  invoke  other  less  probable  traits  to  account 
for  any  fact  which  these  seem  fairly  adequate  to  explain.  For 
instance,  if  the  intellectual  achievement  of  men  was  found  to  be 
superior  to  that  of  women  we  could  explain  it  either  by  the 
indirect  effect  of  physical  strength  and  bodily  fitness  or  by  an 
actual  dift'erence  in  intellect  or  by  the  zeal  and  activity  due  to 
the  fighting  instinct.  Our  rule  would  be  to  exhaust  first  the 
influence  of  the  known  physical  differences  and  second  the 
influence  of  the  instinct  in  question.  Only  if  these  were 
inadequate  should  we  resort  to  the  hypothetical  cause  of  differ- 
ences in  purely  intellectual  caliber. 

Havelock  Ellis  ['94,  '04]  chooses  as  general  sex  differences 
the  less  variability  and  the  greater  affectability  and  primitiveness 
of  the  female  mind.  The  first  point  has  been  discussed  fully.  By 
affectability  he  means  not  only  greater  impressibility  by  and 
responsiveness  to  stimuli  of  all  sorts,  but  also  less  inhibition  of 
the  emotions  and  other  instinctive  reactions.  The  fact  seems 
indubitable  though  its  exact  amount  can  not  be  even  roughly 
estimated.  Not  only  the  superiority  in  tests  of  perceptual  power 
and  the  greater  suggestibility  which  we  have  noted,  but 
also  the  relative  frequency  of  dreams,  trance  states  and  emotional 
outbreaks  and  the  common  differences  between  our  treatment  of 
the  men  and  of  the  women  with  whom  we  are  associated,  witness 
to  it.  In  his  evidence  for  the  discussions  of  the  primitive  nature 
4 


50  Educational  Psychology 

of  women  Mr.  Ellis  seems  to  have  physique  in  view  primarily. 
How  far  women  resemble  uncivilized  races  and  children  in  mental 
make-up  is,  to  me  at  least,  not  at  all  clear. 

The  same  author  emphasizes,  as  so  many  others  have  done,  the 
fact  of  female  dependence  or  lack  of  aggressiveness  in  intellect. 
The  qualities  that  we  call  original,  constructive,  organizing  and 
critical  are  ill  defined  and  comparisons  are  hard  to  arrange 
because  men  and  women  have  devoted  the  active  power  of  the 
intellect  to  such  different  fields.  Comparison  of  the  most  eminent 
representatives  from  both  sexes  is  obviously  unfair  in  so  far  as 
men  are  more  variable. 

If  we  are  to  believe  the  novelists  and  playwrights,  women  are 
more  concerned  with  their  own  feelings  and  personalities  than 
men,  are  emotionally  more  subjective.  This  is  not  inconsistent 
with  the  existence  of  greater  sympathy  of  the  motherly  sort,  nor 
with  the  possibly  superior  gifts  of  men  in  the  examination  and 
intellectual  manipulation  of  subjective  conditions.  An  interesting 
bit  of  evidence  supports  the  conventional  view  of  fiction.  Many 
people  carry  on  as  a  systematic  day  dream  a  continued  story 
in  which  they  figure  and  which  possesses  its  interest  from  the 
chance  it  gives  to  think  pleasantly  of  oneself.  According  to 
Learoyd  ['96]  three  and  a  half  times  as  many  women  as  men 
do  this  (46.7  per  cent  and  13.5  per  cent). 

On  the  whole  the  differences  reported  in  the  case  of  the  less 
easily  measurable  features  of  intellect,  character  and  behavior 
are  of  the  same  order  of  magnitude  as  those  found  in  objective 
tests.  They  do  not  require  any  amendment  of  the  general  rule 
that  sex  is  the  cause  of  only  a  small  fraction  of  the  diflferences 
between  individuals.  The  differences  of  men  from  men  and  of 
women  from  women  are  nearly  as  great  as  the  differences  between 
men  and  women. 


CHAPTER  IV 

The  Influence  of  Remote  Ancestry  or  Race 

The  Possibility  of  Racial  Mental  Differences 

Men  are  mentally  like  one  another  and  unlike  dogs  or  horses 
because  men  spring  from  a  presumably  common  remote  ancestry 
which  was  not  the  ancestry  of  dogs  and  horses.  Men,  dogs  and 
horses  are  more  alike  mentally  than  men,  dogs,  horses,  earth- 
worms and  clams  are,  because  presumably  men,  dogs  and  horses 
spring  from  a  common  ancestry  which  was  not  the  ancestry  of 
earthworms  or  clams.  Certain  men,  for  example  the  American 
Indians,  springing  from  a  common  ancestry  which  was  not  the 
ancestry  of  Europeans,  may  be  expected  to  be  mentally  more 
like  one  another  than  like  Europeans,  if  their  common  ancestry 
differed  mentally  from  that  of  Europeans. 

A  distinct  race  is  a  group  of  men  who  to  a  considerable  extent 
have  in  common  the  same  remote  ancestry,  its  present  descendants 
being  to  a  considerable  extent  confined  to  that  group.  The  more 
they  all  hark  back  to  just  the  same  ancestry,  and  the  more 
exclusively  they  represent  the  present  product  of  this  ancestry, 
the  more  distinct  a  race  they  will  be. 

A  race  that  is  thus  distinct  in  ancestry  is  commonly  distinct 
in  some  physical  traits  also.  If  its  remote  ancestry  differed  from 
the  remote  ancestry  of  other  races  in  mental  traits,  as  it  probably 
did  to  at  least  some  slight  extent,  the  race  has  a  probability  of 
differing  from  other  races  in  these  traits.  So  also  if  the  race 
has  differed  from  other  races  in  the  nature  or  amount  of  selection, 
natural  or  artificial,  on  the  basis  of  mental  traits.  An  individual 
may  thus,  by  original  nature,  possess  certain  racial  mental 
tendencies.  His  position  on  the  scale  for  any  mental  trait  may 
be  due  in  part  to  his  membership  in  a  certain  race, — that  is,  to 
his  origin  from  a  certain  remote  ancestry. 

The  influence  of  remote  ancestry  cannot  however  be  isolated 
for  measurement  at  all  perfectly.    The  pedigrees  of  human  stocks, 

(51) 


52  Educational  Psychology 

at  least  of  the  modern  civilized  stocks,  are  not  clear  enough,  and 
the  influence  of  similarity  in  remote  ancestry  is  hard  to  distinguish 
from  that  of  similarity  in  training.  Many  of  the  mental  similarities 
of  an  Indian  to  Indians  and  of  his  differences  from  Anglo-Saxons 
disappear  if  he  happens  to  be  adopted  and  brought  up  as  an 
Anglo-Saxon. 

So,  though  the  best  way  to  think  of  the  problem  is  to  picture 
the  hereditary  relations  of  all  men  and  to  measure  the  original  like- 
nesses within  the  same  strains  and  the  differences  between  strains, 
apart  from  all  influences  of  training,  the  facts  at  hand  do  not  so 
group  themselves.  The  facts  are  measurements  of  the  differences 
between  groups  which  are  distinct  to  an  unknown  degree  in  traits 
which  are  influenced  by  training  to  an  unknown  degree.  Any 
conclusion  will  depend  upon  one's  estimates  of  these  two  unknown 
quantities. 

I  shall  report  one  sample  study  of  the  topic  in  the  case,  of  great 
importance  to  American  education,  of  differences  between  whites 
and  negroes  in  scholarship  in  the  high  school.  I  shall  then  sum- 
marize the  results  of  other  measurements  of  racial  mental  differ- 
ences ;  and,  lastly,  describe  the  attitude  which  science  recommends 
toward  the  apparently  original  differences  in  intellect,  character 
and  temperament  which  have  not  been  measured. 

A  Sample  Study  of  Racial  Differences 

Mr.  Mayo  [in  a  study  as  yet  unprinted]  secured  the  academic 
records  of  150  negroes*  who  entered  the  high  schools  of  New 
York  City  during  the  period  from  1902  om  For  each  such 
record  he  got  a  white  pupil'sf  record  selected  under  the  same 
conditions.  It  is  impossible  to  tell  exactly  whether  and  how  far 
the  two  groups  of  pupils  thus  taken  represent  dissimilar  samplings 
of  the  two  total  groups,  negroes  and  whites  in  New  York  City. 
In  my  opinion  the  samplings  are  closely  similar.  There  are  no 
measurements  of  the  extent  to  which  residence  in  New  York 
selects  the  more  scholarly  of  negroes  from  the  country,  or  of  the 
extent  to  which  entrance  to  high  school  selects  differently  from 

*A  negro  being  defined  as  an  individual  reported  as  a  negro  by  school 
officers.     Mulattoes  are  of  course  frequent. 

f  A  white  pupil  being  defined  as  an  individual  reported  as  such  by  school 
officers.  There  may  in  rare  cases  have  been  some  slight  mixture  of  negro 
blood. 


The  Influence  of  Remote  Ancestry  or  Race  53 

the  negroes  in  New  York  than  from  the  whites.  In  general, 
selection  by  entrance  to  the  pubHc  high  schools  is  narrow  but 
democratic ;  and  in  Mr.  Mayo's  opinion  and  my  own  the  high 
school  gets  a  somewhat,  but  not  much,  higher  selection  from  the 
colored  than  from  the  white  youth.  That  is,  in  our  opinion,  the 
superiority  of  the  colored  in  high  school  to  the  colored  outside  is 
greater,  but  not  much  greater,  than  the  superiority  of  the  whites  in 
high  school  to  the  whites  outside. 

Whatever  be  the  difference  in  the  selection  of  the  two  groups, 
colored  beginners  in  high  schools  in  New  York  City  differ  from 
whites  in  their  careers  there  as  follows : 

( 1 )  On  the  average  they  are  seven  months  older,  only  36  per  cent 

of  them  being  as  young  as  the  median  white. 

(2)  They  continue  in  the  high  school  longer. 

(3)  In  achievement  in  the  different  studies  they  are  somewhat, 

but  not  very  much,  inferior.  The  general  tendency  is  for 
only  three-tenths  of  them  to  reach  the  median  record  for 
whites. 

(4)  The  difference  is  greatest  in  the  case  of  English,  in  which 

only  24  per  cent  of  the  colored  pupils  reach  or  exceed 
the  median  for  whites. 

Table  7  gives  a  sample  of  Mr.  Mayo's  measurements  of  the 
differences.     Fig.  19  presents  the  facts  graphically. 

Mr.  Mayo  also  measured  the  differences  in  variability,  as  far 
as  he  could  from  the  arbitrary  measures  afforded  by  school  marks. 
For  the  details  the  reader  must  turn  to  the  full  tables  in  his  report 
(which  will  be  printed  at  an  early  date),  one  sample  table  and 
the  general  drift  of  the  results  being  all  that  can  be  presented 
here.  The  records  of  colored  pupils  were  perhaps  a  very  little 
less  variable  than  the  whites.  Thus,  in  the  score  for  total  scholar- 
ship (Table  7),  80  per  cent  of  the  colored  pupils  are  included 
within  a  range  of  193^  points  on  the  scholarship  scale,  while  to 
include  80  per  cent  of  the  white  pupils  requires  a  range  of  20 
points.  The  corresponding  figures  for  the  inclusion  of  60  per  cent 
are  14^  and  14  points.  The  figures  for  the  inclusion  of  50 
per  cent  are  9  and  10^.  The  figures  for  the  inclusion  of  90  per  cent 
(or,  to  be  exact,  90.7  per  cent)  are  33  and  31.  The  comparison 
in  variability  is,  as  in  the  case  of  the  sexes,  of  great  practical 
importance.  The  ability  of  a  hundred  of  its  most  gifted  represent- 
atives often  counts  more  for  a  nation's  or  a  race's  welfare  than 


54 


Educational  Psychology 


the  ability  of  a  million  of  its  mediocrities.  The  fact  that  the 
colored  pupils,  though  clustered  more  closely  at  the  center,  range 
to  nearly  or  quite  as  high  grades  as  do  the  white  is  thus  noteworthy. 

TABLE  7. 
White  and  Colored  Pupils  Compared  in  Scholarship  in   New  York 

City  High  Schools. 
Median  of  all  marks 


in  the  first  trials  (that 

is,  excluding  marks 

for  courses  repeated 

after  failure) 

Number 

of 

white 

pupils 

Number 
■"■       of 
colored 
pupils 

24—25 
26 — 27 
28 — 29 

I 

30—31 

32—33 

I 

34—35 
36—37 
38—39 

I 

40—41 

I 

5 

42—43 

2 

44—45 
46—47 

48—49 

2 
2 
I 

50—51 
52—53 

4 

4 

21 
6 

54—55 
56—57     ■ 
58—59 
60 — 61 

I 

2 

6 

18 

9 

7 
12 

17 

62—63 
64—65 
66—67 
68—69 

21 

13 
12 
II 

22 
16 
13 

15 

70—71 

10 

2 

72—73 

16 

I 

74—75 
76—77 
78—79 
80 — 81 

8 
3 
4 
5 

3 
3 

1 

82—83  . 
84—85 
86—87 
88—89 

2 

2 

3 

I 

I 

90—91 

2 

92—93 

I 

[ 

Median 


66 


62 


The  Influence  of  Remote  Ancestry  or  Race 


55 


The  Results  of  Measurements  of  Racial  Mental  Differences 

In  summarizing  the  measurements  of  racial  mental  differences 
I  shall  in  the  main  quote  the  admirable  account  by  Woodworth 
['lo]. 

The  different  races  of  men  have  been  compared  by  objective 
measurements  in  respect  to  the  keenness  of  the  senses,  but  in 
few  traits  besides.  The  reports  of  travelers  gave  rise  to  the 
doctrine  that  primitive  races  excelled  modern  Europeans  in  powers 


BT 


W. 


£k 


I 
20 


40 


60 


80 


Fig.  19.  Comparison  of  white  pupils  (continuous  line)  and  colored  pupils 
(dotted  line)  in  respect  to  scholarship  in  the  high  school.  The  horizontal 
scale  is  for  the  median  of  all  marks  obtained  by  an  individual  except  those 
obtained  in  courses  repeated  because  of  failure.  The  marks  in  these  schools 
are  on  a  o  -  100  scale. 

of  vision,  hearing  and  smell.     Skepticism  concerning  this  doctrine 
has  led  to  many  measurements  by  anthropologists. 

"Ranke  on  testing  natives  of  Brazil,  a  race  notable  for 
its  feats  of  vision,  found  that  their  ability  to  discern  the  position 
of  a  letter  or  similar  character  at  a  distance,  though  good,  was 
not  remarkable,  but  fell  within  the  range  of  European  powers. 
The  steppe-dwelling  Kalmuks,  also  renowned  for  distant  vision, 
being  able  to  detect  the  dust  of  a  herd  of  cattle  at  a  greater 
distance  with  the  naked  eye  than  a  European  could  with  a 
telescope,  have  also  been  examined ;  and  their  acuity  was  indeed 
found  to  be  very  high,   averaging   considerably   above   that   of 


56  Educational  Psychology 

Europeans ;  yet  only  one  or  two  out  of  the  forty  individuals 
tested  exceeded  the  European  record,  while  the  great  majority 
fell  within  the  range  of  good  European  eyes.  Much  the  same 
result  has  been  obtained  from  Arabs,  Egyptians  and  quite  a 
variety  of  peoples.  Among  the  most  reliable  results  are  those 
of  Rivers  on  a  wholly  unselected  Papuan  population.  He  found 
no  very  exceptional  individual  among  115  tested,  yet  the  average 
was  somewhat  better  than  that  of  Europeans.  I  had  myself, 
through  the  kindness  of  Dr.  McGee,  the  opportunity  of  testing 
individuals  from  quite  a  variety  of  races  at  the  St.  Louis  Fair 
in  1904,  and  my  results  agree  closely  with  those  already  cited, 
though  I  did  not  find  any  cases  of  very  exceptional  powers  among 
about  300  individuals.  There  were  a  number  who  exceeded  the 
best  of  the  200  whites  whom  I  also  tested  under  the  same 
conditions,  but  none  who  exceeded  or  equaled  the  record  of  a 
few  individuals  who  have  been  found  in  the  German  army. 
Indians  and  Filipinos  ranked  highest,  averaging  about  10  per  cent 
better  than  whites,  when  all  individuals  of  really  defective  vision 
were  excluded.  The  amount  of  overlapping  is  indicated  by  stating 
that  65-75  per  cent  of  Indians  and  Filipinos  exceeded  the  average 
for  whites."  ['10,  p.  175] 

There  are  racial  differences  in  hearing,  as  tested  by  the  ticking 
of  a  watch  or  a  click  artificially  made.  The  Papuans  were  found 
to  be  inferior  to  Europeans.  Bruner  ['08,  p.  92]  found  that 
only  five  per  cent  of  Filipinos  equalled  or  exceeded  the  median 
white  American.  The  per  cent  for  Indians  with  more  or  less 
school  training  was  38.  Of  the  18  Patagonians,  Ainus  and 
reputed  Pygmies,  none  equalled  the  median  white  American. 
These  differences  are  probably  due  in  large  measure  and  possibly 
in  toto  to  the  greater  cleanliness,  freedom  from  injury  to  the  ear, 
and  special  training  in  hearing  a  click  transmitted  by  a  telephone 
Of  the  sense  of  touch  and  the  sense  of  pain  Woodworth  says : 
"The  sense  of  touch  has  been  little  examined.  McDougall  found 
among  the  Papuans  a  number  with  extremely  fine  powers  of  dis- 
crimination by  the  skin.  The  difference  between  two  points  and 
one  could  be  told  by  these  individuals  even  when  the  two  points 
were  brought  very  close  together ;  on  the  average,  the  Papuans 
tested  excelled  Europeans  considerably  in  this  test.  On  the  other 
hand,  Indians  and  Filipinos,  and  a  few  Africans  and  Ainu,  tested 
in  the  same  manner,  seem  not  to  differ  perceptibly  from  whites. 


The  Influence  of  Remote  Ancestry  or  Race  57 

The  pain  sense  is  a  matter  of  some  interest,  because  of  the 
fortitude  or  stoHdity  displayed  by  some  races  towards  physical 
suffering.  It  may  be,  and  has  been  conjectured,  that  the  sense 
for  pain  is  blunt  in  these  races,  as  it  is  known  to  be  in  some 
individuals  who  have  allowed  themselves  to  be  burned  without 
flinching,  and  performed  other  feats  of  fortitude.  The  pain 
sense  is  tested  by  applying  gradually  increasing  pressure  to  some 
portion  of  the  skin,  and  requiring  the  person  tested  to  indicate 
w'hen  he  first  begins  to  feel  pain.  Now  as  a  matter  of  fact,  the 
results  of  McDougall  on  the  Papuans,  and  those  of  Dr.  Bruner 
and  myself  on  Indians,  Filipinos,  Africans  and  Ainu,  are  in  close 
agreement  on  this  point.  Greater  pressure  on  the  skin  is  needed 
to  produce  pain  in  each  of  these  races  than  in  whites.  This  is 
the  average  result,  but  in  this  test  the  distribution  of  the  cases  is 
specially  important.  Though  most  whites  feel  pain  at  or  about  a 
certain  small  pressure,  there  is  quite  a  respectable  minority  who 
give  no  sign  till  much  higher  pressures  are  reached,  their  results 
corresponding  very  closely  to  those  of  the  majority  of  Indians. 
And  similarly,  a  minority  of  Indians  feel  pain  at  much  lower 
pressures  than  the  bulk  of  their  fellows,  falling  into  the  ranks 
of  the  white  man.  In  each  group,  the  distribution  is  bimodal,  or 
aggregated  about  two  points  instead  of  one ;  but  whites  are  prin- 
cipally aggregated  about  the  lower  center,  and  Indians  and  other 
races  about  the  higher  center.  Introspection  comes  to  our  aid  in 
explaining  this  anomaly,  for  it  shows  that  there  is  some  difficulty 
in  telling  just  when  the  pressure  becomes  painful.  If  one  is 
satisfied  with  slight  discomfort,  a  moderate  pressure  will  be 
enough ;  but  if  a  sharp  twinge  is  demanded,  the  pressure  must 
be  considerably  increased.  Most  whites,  under  the  conditions  of 
the  test,  are  satisfied  with  slight  discomfort,  while  my  impression 
in  watching  the  Indians  was  that  they  were  waiting  to  be  really 
hurt.  The  racial  difference  would  accordingly  be  one  in  the 
conception  of  pain,  or  in  understanding  the  test,  rather  than  in 
the  pain  sense. 

On  the  whole,  the  keenness  of  the  senses  seems  to  be  about  on 
a  par  in  the  various  races  of  mankind."     ['10,  pp.  176-177] 

With  respect  to  racial  differences  in  speed  of  brain  action  and 
in  certain  objective,  though  somewhat  trivial,  tests  of  intellect, 
Woodworth  says : 


58  Educational  Psychology 

"Some  interest  attaches  to  tests  of  the  speed  of  simple  mental 
and  motor  performances,  since  though  the  mental  process  is 
very  simple,  some  indication  may  be  afforded  of  the  speed  of 
brain  action.  The  reaction  time  test  has  been  measured  on 
representatives  of  a  few  races,  with  the  general  result 
that  the  time  consumed  is  about  the  same  in  widely  different 
groups.  The  familiar  "tapping  test,"  which  measures  the  rate 
at  which  the  brain  can  at  will  discharge  a  series  of  impulses  to 
the  same  muscle,  was  tried  at  St.  Louis  on  a  wide  variety  of  folk, 
without  disclosing  marked  differences  between  groups.  The 
differences  were  somewhat  greater  when  the  movement,  besides 
being  rapid,  had  to  be  accurate  in  aim.  The  Eskimos  excelled 
all  others  in  this  latter  test,  while  the  poorest  record  was  made 
by  the  Patagonians  and  the  Cocopa  Indians — which  groups  were, 
however,  represented  by  only  a  few  individuals.  The  Filipinos, 
who  were  very  fully  represented,  seemed  undeniably  superior  to 
whites  in  this  test,  though,  of  course,  with  plenty  of  over- 
lapping  

"Equitable  tests  of  the  distinctly  intellectual  processes  are  hard 
to  devise,  since  much  depends  on  the  familiarity  of  the  material 
used.  Few  tests  of  this  nature  have  as  yet  been  attempted  on 
different  races. 

"There  are  a  number  of  illusions  and  constant  errors  of  judgment 
which  are  well  known  in  the  psychological  laboratory,  and  which 
seem  to  depend,  not  on  peculiarities  of  the  sense  organs,  but  on 
quirks  and  twists  in  the  process  of  judgment.  A  few  of  these 
have  been  made  the  matter  of  comparative  tests,  with  the  result 
that  peoples  of  widely  different  cultures  are  subject  to  the  same 
errors,  and  in  about  the  same  degree.  There  is  an  illusion  which 
occurs  when  an  object,  which  looks  heavier  than  it  is,  is  lifted 
by  the  hand ;  it  then  feels,  not  only  lighter  than  it  looks,  but  even 
lighter  than  it  really  is.  The  contrast  between  the  look  and  the 
feel  of  the  thing  plays  havoc  with  the  judgment.  Women  are, 
on  the  average,  more  subject  to  this  illusion  than  men.  The 
amount  of  this  illusion  has  been  measured  in  several  peoples,  and 
found  to  be,  with  one  or  two  exceptions,  about  the  same  in  all. 
Certain  visual  illusions,  in  which  the  apparent  length  or  direction 
of  a  line  is  greatly  altered  by  the  neighborhood  of  other  lines, 
have  similarly  been  found  present  in  all  races  tested,  and  to  about 
the  same  degree.    As  far  as  they  go,  these  results  tend  to  show 


The  Influence  of  Remote  Ancestry  or  Race  59 

that  simple  sorts  of  judgment,  being  subject  to  the  same  disturb- 
ances, proceed  in  the  same  manner  among  various  peoples ;  so 
that  the  similarity  of  the  races  in  mental  processes  extends  at 
least  one  step  beyond  sensation. 

"The  mere  fact  that  members  of  the  inferior  races  are  suitable 
subjects  for  psychological  tests  and  experiments  is  of  some  value 
in  appraising  their  mentality.  Rivers  and  his  collaborators 
approached  the  natives  of  Torres  Straits  with  some  misgivings, 
fearing  that  they  would  not  possess  the  necessary  powers  of  sus- 
tained concentration.  Elaborate  introspections,  indeed,  they  did 
not  secure  from  these  people,  but,  in  any  experiment  that  called 
for  straightforward  observation,  they  found  them  admirable 
subjects  for  the  psychologist.  Locating  the  blind  spot,  and 
other  observations  with  indirect  vision,  which  are  usually 
accounted  a  strain  on  the  attention,  were  successfully  per- 
formed. If  tests  are  put  in  such  form  as  to  appeal  to  the 
interests  of  the  primitive  man,  he  can  be  relied  on  for 
sustained  attention.  Statements  sometimes  met  with  to  the 
effect  that  such  and  such  a  tribe  is  deficient  in  power  of 
attention,  because,  when  the  visitor  began  to  quiz  them  on 
matters  of  linguistics,  etc.,  they  complained  of  headache  and  ran 
away,  sound  a  bit  naive.  Much  the  same  observations  could  be 
reported  by  college  professors,  regarding  the  natives  gathered  in 
their  class  rooms. 

"A  good  test  for  intelligence  would  be  much  appreciated  by  the 
comparative  psychologist,  since,  in  spite  of  equal  standing  in 
such  rudimentary  matters  as  the  senses  and  bodily  movement, 
attention  and  the  simpler  sorts  of  judgment,  it  might  still  be 
that  great  differences  in  mental  efficiency  existed  between  different 
groups  of  men.  Probably  no  single  test  could  do  justice  to  so 
complex  a  trait  as  intelligence.  Two  important  features  of 
intelligent  action  are  quickness  in  seizing  the  key  to  a  novel 
situation,  and  firmness  in  limiting  activity  to  the  right  direction, 
and  suppressing  acts  which  are  obviously  useless  for  the  purpose 
in  hand.  A  simple  test  which  calls  for  these  qualities  is  the 
so-called  "form  test."  There  are  a  number  of  blocks  of  different 
shapes,  and  a  board  with  holes  to  match  the  blocks.  The  blocks 
and  board  are  placed  before  a  person,  and  he  is  told  to  put  the 
blocks  in  the  holes  in  the  shortest  possible  time.  The  key  to 
the  situation  is  here  the  matching  of  blocks  and  holes  by  their 


6o  Educational  Psychology 

shape;  and  the  part  of  intelligence  is  to  hold  firmly  to  this 
obvious  necessity,  wasting  no  time  in  trying  to  force  a  round 
block  into  a  square  hole.  The  demand  on  intelligence  certainly 
seems  slight  enough ;  and  the  test  would  probably  not  differentiate 
between  a  Newton  and  you  or  me ;  but  it  does  suffice  to  catch 
the  feeble-minded,  the  young  child,  or  the  chimpanzee,  as  any  of 
these  is  likely  to  fail  altogether,  or  at  least  to  waste  much  time 
in  random  moves  and  vain  efforts.  This  test  was  tried  on 
representatives  of  several  races  and  considerable  differences 
appeared.  As  between  whites,  Indians,  Eskimos,  Ainus,  Filipinos 
and  Singhalese,  the  average  differences  were  small,  and  much 
overlapping  occurred.  As  between  these  groups,  however,  and 
the  Igorot  and  Negrito  from  the  Philippines  and  a  few  reputed 
Pygmies  from  the  Congo,  the  average  differences  were  great,  and 
the  overlapping  was  small.  Another  rather  similar  test  for 
intelligence,  which  was  tried  on  some  of  these  groups,  gave  them 
the  same  relative  rank.  The  results  of  the  test  agreed  closely 
with  the  general  impression  left  on  the  minds  of  the  experimenters 
by  considerable  association  with  the  people  tested.  And,  finally, 
the  relative  size  of  the  cranium,  as  indicated,  roughly,  by  the 
product  of  its  three  external  dimensions,  agreed  closely  in  these 
groups  with  their  appearance  of  intelligence,  and  with  their 
standing  in  the  form  test.  If  the  results  could  be  taken  at  their 
face  value,  they  would  indicate  differences  of  intelligence  between 
races,  giving  such  groups  as  the  Pygmy  and  Negrito  a  low 
station  as  compared  with  most  of  mankind.  The  fairness  of  the 
test  is  not,  however,  beyond  question ;  it  may  have  been  of  a 
more  unfamiliar  sort  to  these  wild  hunting  folk  than  to  more 
settled  groups.  This  crumb  is,  at  any  rate,  about  all  the  testing 
psychologist  has  yet  to  offer  on  the  question  of  racial  differences 
in  intelligence."  ['lo,  pp.  179-181] 

The  difference  between  civilized  whites  and  Negritos  mentioned 
by  Professor  Woodworth  is  shown  graphically  in  Fig.  20  for 
the  first  trial  in  placing  the  blocks  and  in  Fig.  21  for  the  third 
trial.  In  the  first  trial  only  9^  per  cent  of  the  Negritos  were 
as  quick  as  the  median  white ;  in  the  third  trial  no  one  of  them 
was,  the  best  individual  of  the  twenty-two  just  not  reaching  the 
speed  of  the  median  white.  The  Negritos  also  made  many  more 
errors.  The  reputed  Pygmies  were  still  less  capable  than  the 
Negritos.     The  Pygmies  apparently  did  not  do  so  well  in  this 


The  Influence  of  Remote  Ancestry  or  Race 


6i 


test  as  the  so-called  'feeble-minded'  and  'higher  grade  imbeciles' 
confined  in  state  asylums  in  Massachusetts  and  Connecticut. 

Havelock  Ellis  ['04]  studied  the  relation  of  race  to  amount  and 
kind  of  achievement  in  the  case  of  the  1030  most  eminent  British 
careers  from  the  4th  to  the  19th  century.  He  verifies  the  opinion 
that  the  Scotch  have  a  larger  percentage  of  men  of  great  intellect 
than  the  English,  Welsh  or  Irish.     The  most  marked  diflference 


_i 1 


16 


i50 


15     30    45    60     76    90    105 


Fig.  20  (upper  diagram).  Comparison  of  v/hites  (continuous  lines)  and 
Negritos  (dotted  lines)  in  respect  to  time  taken  to  put  variously  shaped 
blocks  in  holes  to  match.  The  horizontal  scale  is  for  time  in  seconds,  first 
trial. 


Fig.  21  (lower  diagram), 
third  trial  were  used. 


As  in  Fig.  20,  except  that  the  records  in  the 


which  he  finds  is  between  the  Scotch  and  Irish  in  the  case  of 
ability  in  Science  and  in  Acting.  Of  the  120  men  of  science,  21 
were  Scotch  and  only  i  Irish,  while  of  the  42  actors  6  were  Irish 
and  none  were  Scotch.  He  also  finds  signs  of  differences  in  the 
character  of  the  scientific  work  done  by  men  from  different  sec- 
tions representing  somewhat  different  racial  stocks.       He  writes: 


62  Educational  Psychology 

"Psychologically  it  is  not  difficult  to  detect  a  distinct  character 
in  English  scientific  genius,  according  as  it  springs  from  the 
Anglo-Danish  district  or  the  East-Anglian  focus  or  the  south- 
western focus,  although  I  am  not  aware  that  this  has  been  pointed 
out  before.  The  Anglo-Danish  district  may  here  be  fairly  put 
first,  not  only  on  account  of  the  large  number  of  scientific  men  it 
has  wholly  or  in  part  produced,  but  also  on  account  of  the  very 
high  eminence  of  some  among  them.  The  Anglo-Dane  appears 
to  possess  an  aptitude  for  mathematics  which  is  not  shared  by  the 
native  of  any  other  English  district  as  a  whole,  and  it  is  in  the 
exact  sciences  that  the  Anglo-Dane  triumphs.*  Newton  is  the 
supreme  figure  of  Anglo-Danish  science;  it  will  be  noted  that 
he  belongs  to  the  East-Anglian  border,  and  by  his  mother  is 
claimed  by  Rutland,  a  little  county  which,  I  am  inclined  to  think, 
really  belongs  psychologically  and  perhaps  ethnologically  to  East 
Anglia.  The  combination  of  the  Anglo-Dane  and  the  East 
Anglian  seems  highly  favorable  to  scientific  aptitude ;  the  abstract- 
ing tendency  of  the  Anglo-Dane,  and  the  exaggerated 
independence  of  his  character,  with  the  difficulty  he  finds  in  taking 
any  other  point  of  view  than  his  own,  are  happily  tempered  by 
the  more  cautious  and  flexible  mind  of  the  East  Anglian.  Darwin 
(who  also  belonged  to  the  Welsh  Border)  belonged  in  part,  like 
Newton,  to  the  East  Anglian  border  of  the  Anglo-Danish  district, 
and  also  (somewhat  remotely)  to  Norfolk,  a  county  which  con- 
tains many  Danish  elements.  The  science  of  the  Anglo-Danish 
district  is  not  exclusively  mathematical,  and  geolog>'  especially 
owes  much  to  the  Anglo-Dane ;  it  will  be  remembered  that  geology^ 
was  one  of  the  first  sciences  to  attract  Darwin. 

"  The  East  Anglian  is  in  scientific  matters  drawn  to  the  concrete, 
and  shows  little  or  no  mathematical  aptitude.  He  is  a  natural 
historian  in  the  widest  sense.  He  delights  in  the  patient  collection 
of  facts,  and  seeks  to  sift,  describe,  co-ordinate,  and  classify  them. 
In  his  hands  science  becomes  almost  an  art.  Gilbert  illustrates 
East  Anglian  scientific  methods  in  the  inorganic  world,  Ray  in 
the  organic,  and  Francis  Bacon,  though  he  cannot  himself  be 
classed  among  men  of  science,  has  in  the  Novum  Organum  and 
elsewhere  presented  a  picture  of  scientific  method  as  it  most 
naturally  appears  to  the  East  Anglian  mind. 

*The  mathematical  tendencies  of  Cambridge  are  due  to  the  fact  that 
Cambridge  drains  the  ability  of  nearly  the  whole  Anglo-Danish  district. 


The  Influence  of  Remote  Ancestry  or  Race  63 

"It  is  not  easy  to  see  anything  specific  or  definitely  Brythonic 
in  the  scientific  activities  of  the  Welsh  Border.  At  most  it  may 
be  said  that  there  is  some  tendency  for  science  here  to  take  on  a 
technological  character  and  to  become  associated  with  the  artistic 
crafts.  The  scientific  men  found  here  often  belong  only  in 
part  to  the  district,  and  many  of  them  seem  to  possess  the 
psychological  characters  of  the  southwestern  focus. 

''The  scientific  characters  of  the  southwestern  focus  are  quite 
clear,  and  definitely  distinct  from  those  of  either  the  Anglo- 
Danish  district  or  the  East  Anglian  focus.  What  we  find  here 
is  the  mechanical  impulse,  and  more  especially  the  physiological 
temper,  the  instinct  to  seek  out  the  driving  forces  of  A-ital 
phenomena.  It  is  on  this  account  that  Harvey,  though  of 
Kentish  family,  may  be  said  to  belong  psychologically  to  this 
focus,  as  also  Stephen  Hales,  though  he  belonged  partly  to 
Kent  and  partly  to  East  Anglia.  The  great  scientific  physicians 
belong  here  (the  surgeons  are  largely  East  Anglian),  with 
Sydenham  at  the  head  and  Glisson.  Huxley,  again,  is  a  typical 
figure.  Inventors  are  numerous,  for  the  scientific  men  of  this 
region  have  frequently  been  enamoured  of  practical  problems, 
and  just  as  they  have  been  pioneers  in  the  physical  world,  so 
in  science  they  have  sought  rather  to  make  discoveries  than 
to  formulate  laws.  Thus  in  astronomy  we  have  Adams,  and 
one  of  the  greatest  and  most  typical  scientific  men  of  this  region 
was  Thomas  Young."     ['04,  pp.  68-71] 

These  last  differences  are  not  measured,  but  if  they  exist  at 
all  they  are  surely  very  slight ;  for  even  the  most  striking  differ- 
ence, that  between  the  Scotch  and  Irish  in  science  and  in  acting, 
is  really  a  very  small  difference.  Even  supposing  circumstances 
of  religion,  education  and  the  like  to  have  had  no  part  in  it 
and  so  attributing  the  whole  of  the  difference  found  to  race,  the 
facts  found  could  be  explained  by  supposing  the  two  races  to 
differ  in  the  capacity  for  science  by  much  less  than  the  amount 
shown  in  Fig.  22.  Similarly  in  the  case  of  acting.  A  very  slight 
difference  between  two  groups  in  central  tendency  may  (and 
will,  except  for  contrary  influences  from  differences  in  variability) 
make  an  enormous  dift'erence  between  the  percentages  from  the 
two  groups  that  possess  a  very  high  degree  of  the  trait  in  question. 
Indeed  I  have  quoted  Ellis's  conjectures  chiefly  as  a  sample  of 
how,  on  the  one  hand,  a  striking  difference  between  extreme 


64  Educational  Psychology 

representatives  may  mislead  one  and  of  how,  on  the  other  hand, 
a  very  small  general  difference  between  two  races  may  by  its 
effect  in  producing  many  more  men  of  very  high  ability,  advance 
the  social  condition  of  the  favored  race. 

The  Interpretation  of  the  Differences  Between   One  Race  and 
Another  in  Achievement 

The  moderation  of  the  findings  by  psychologists  is  in  striking 
contrast  with  the  first  and  common  impression  made  by  the 
history  and  present  status  of  different  races  of  men.  The  modern 
European,  who  can  kill  a  hundred  of  a  race  in  an  hour,  or  buy 
up  their  entire  property  with  the  results  from  one  day  of  his 


Fig.  22. 

labor,  or  get  any  of  the  results  one  of  them  desires  in  a  tenth 
of  the  time  that  they  take,  seems  to  be  far  more  capable  than 
they.  The  Chinese,  who  resists  all  that  we  think  he  ought  to 
crave,  seems  obviously  to  have  a  temperament  radically  different 
from  ours.  Large,  glaring  differences  mark  the  achievements  of 
races  and  seem  to  need  large  differences  in  nature  as  their  origins. 
The  most  noticeable  fact  about  the  races  of  men  seems  to  be 
their  great  mental  variety.  Under  the  deliberate  scrutiny  of 
actual  measurements,  however,  what  seemed  to  be  large  differ- 
ences shrink  to  five  or  ten  per  cent,  and  what  seemed  to  be  wide 
gaps  are  bridged.  No  two  races  have  been  measured  which 
do  not  overlap  mentally  whatever  be  the  trait  measured. 

The  first  thing  to  note  in  respect  to  the  apparent  conflict 
between  common  observation  and  precise  experiments  is  that  the 
two  have  not  measured  the  same  traits.  Common  observation 
of  the  African  and  the  European,  for  example,  decides  that  the 
latter  is  superior  in  intellect,  enterprise  and  self-reliance.     Even 


The  Influence  of  Remote  Ancestry  or  Race  65 

when  experiments  show  him  to  be  approximately  equal  in  sense 
keenness,  resistance  to  the  size-weight  illusion,  or  putting  blocks 
in  holes  that  fit  them,  the  claims  of  common  observation  are 
not  necessarily  denied.  The  nature  and  amount  of  race  differ- 
ences in  such  traits  as  intellect,  enterprise  and  self-reliance  cannot 
be  inferred  from  the  amount  of  difference  found  in  sensory  or 
sensori-motor  traits,  but  must  be  studied  directly.  We  do  not 
know  just  what  the  symptoms  of  intellect  are,  but  apparently 
quickness  and  accuracy  in  making  purely  mental  associations, 
ability  to  respond  to  parts  or  elements  of  situations  which  cannot 
be  abstracted  in  reality  but  only  in  thought,  the  consequent  power 
to  devise  new  responses  to  old  situations,  and  a  marked  develop- 
ment of  the  instinctive  satisfaction  in  thought  for  its  own  sake 
are  leading  ones.  Measurements  of  these  traits  in  different  races 
are  much  needed.  In  the  second  place,  two  races  need  not  be 
equally  gifted  because  each  is  equally  well  adapted  to  its  environ- 
ment, if  the  second  race  has  by  superior  enterprise  sought  out 
or  created  a  more  exacting  but  also  more  remunerative 
environment.  The  Bushman  may  count  all  that  he  needs  to  count, 
but  to  put  oneself  in  a  position  that  needs  algebra  and  the 
calculus  may  itself  be  a  symptom  of  superiority.  So  the  complex 
of  qualities  which  is  called  enterprise  remains  largely  untouched 
by  the  psychologist's  tests.  The  very  fact  that  a  certain  test 
seems  to  be  unfair  to  the  Bushman  may  be  evidence  of  his 
inferiority. 

A  third  fact  for  consideration  is  that  although  the  most  rigorous 
thinkers  amongst  anthropologists  are  skeptical  concerning  original 
mental  racial  differences,  the  general  body  of  scientific  opinion 
is  by  no  means  fully  agreed  with  them.  Francis  Galton  ['69,  '92]  in 
a  well  known  chapter  on  "The  Comparative  Worth  of  Dift'erent 
Races"  declares  that,  taking  negroes  on  their  own  intellectual 
ground,  they  still  are  inferior  to  Europeans  by  about  one- 
eighth  of  the  difference  between  say  Aristotle  and  the  lowest 
idiot.  That  is,  he  considers  the  two  groups  to  differ  approxi- 
mately as  shown  in  Fig.  23.     His  argument  is : 

'Thirdly,  we  may  compare,  but  with  much  caution,  the  relative 
position  of  negroes  in  their  native  country  with  that  of  the 
travellers  who  visit  them.  The  latter,  no  doubt,  bring  with  them 
the  knowledge  current  in  civilized  lands,  but  that  is  an  advantage 
of  less  importance  than  we  are  apt  to  suppose.  A  native  chief 
5 


66  Educational  Psychology 

has  as  good  an  education  in  the  art  of  ruHng  men  as  can  be 
desired ;  he  is  continually  exercised  in  personal  government,  and 
usually  maintains  his  place  by  the  ascendency  of  his  character, 
shown  every  day  over  his  subjects  and  rivals.  A  traveller  in 
wild  countries  also  fills,  to  a  certain  degree,  the  position  of  a 
commander,  and  has  to  confront  native  chiefs  at  every  inhabited 
place.  The  result  is  familiar  enough — the  white  traveller  almost 
invariably  holds  his  own  in  their  presence.  It  is  seldom  that 
we  hear  of  a  white  traveller  meeting  with  a  black  chief  whom 
he  feels  to  be  the  better  man.  I  have  often  discussed  this  subject 
with  competent  persons,  and  can  only  recall  a  few  cases  of  the 
inferiority  of  the  white  man, — certainly  not  more  than  might  be 
ascribed  to  an  average  actual  diflference  of  three  grades,  of  which 
one  may  be  due  to  relative  demerits  of  native  education,  and  the 
remaining  two  to  a  difference  in  natural  gifts. 


Fig.  23.  The  original  difference  between  Europeans  (continuous  line)  and 
Negroes  (dotted  line)  in  intellectual  ability,  according  to  Galton. 

"Fourthly,  the  number  among  the  negroes  of  those  whom  we 
should  call  half-witted  men  is  very  large.  Every  book  alluding 
to  negro  servants  in  America  is  full  of  instances.  I  was  myself 
much  impressed  by  this  fact  during  my  travels  in  Africa.  The 
Hxistakes  the  negroes  made  in  their  own  matters  were  so  childish, 
stupid,  and  simpleton-like,  as  frequently  to  make  me  ashamed 
of  my  own  species.  I  do  not  think  it  any  exaggeration  to  say, 
that  their  c  is  as  low  as  our  e,  which  would  be  a  difference 
of  two  grades,  as  before.  I  have  no  information  as  to  actual 
idiocy  among  the  negroes — I  mean,  of  course,  of  that  class  of 
idiocy  which  is  not  due  to  disease."  [Hereditary  Genius,  2nd 
Edition,  '92,  p.  327  f.] 

On  the  other  hand,  common  observation  does  not  as  a  rule 
observe  mental  traits,  but  only  certain  indirect  consequences  of 
them  which  it  is  likely  to  misinterpret.     It  observes  customs,  not 


The  Influence  of  Remote  Ancestry  or  Race  6y 

moral  capacity ;  habits,  not  energy ;  knowledge,  not'  intellect. 
But,  obviously,  the  habits  and  knowledge  possessed  by  a  race 
do  not  measure  its  present  original  nature.  Its  habits  and  knowl- 
edge, its  "civilization"  or  "culture"  are  in  the  main  due  to  the 
original  nature  of  men  long  dead  and  have  come  to  it  by  train- 
ing. The  origination  of  advances  in  civilization  is  a  measure  of 
ability,  but  the  abilities  that  have  originated  them  have  prob- 
ably been  confined  to  a  very  few  men.  A  race  that  originated 
none  of  them  may  now  possess  them  all.  Even  if  a  race  has 
been  completely  isolated,  its  civilization  has  been  originated  by 
only  a  few  of  its  members ;  and  the  chance  of  men  of  great  gifts 
being  born  is  the  result  not  only  of  the  central  tendency  of  a 
race  and  its  variability,  but  also  of  its  size.  Other  things  be- 
ing equal,  there  is  a  far  greater  chance  of  the  birth  of  a  man 
of  great  ability  in  a  tribe  of  a  million  than  in  one  of  a  thousand. 
Since  one  such  man  may  add  to  the  knowledge  and  improve 
the  habits  of  the  entire  group  regardless  of  its  size,  civilization 
will  progress  more  rapidly  in  large  than  in  small  groups,  in  a 
condition  of  isolation. 

The  civilized  races  have  not  remained  isolated  and  have  got 
most  of  their  civilization  from  without.  Of  ten  equally  gifted 
races  in  perfect  intercourse  each  will  originate  only  one  tenth 
of  what  it  gets.  The  original  nature  of  the  Germans  of  to-day  is  not 
much  different  from  that  of  their  ancestors  in  the  time  of  Taci- 
tus, and  their  progress  in  the  meantime  is  not  properly  theirs, 
but  that  of  the  European  world  and  its  American  colony,  each 
of  whose  racial  stocks  has  added  something  to  a  common  fund. 

Again  the  civilization, — the  habits  and  customs, — of  a  race 
need  not  be  in  a  direct  proportion  to  its  intellect,  even  if  entirely 
caused  by  it.  A  very  slight  difference  in  intellect  might  give 
one  real  supremacy  over  another,  enable  it  to  condemn  the 
other  to  servitude  and  so  free  its  own  intellect  from  uninstruct- 
ive  labor.  It  would  thenceforth  progress  in  civilization  much 
more  rapidly  than  the  other.  What  the  mental  ability  of  a  race  ■ 
actually  achieves  is  due  to  the  conditions  under  which  it  oper- 
ates, and  a  race  may  put  on  or  put  off  such  conditions  or  have 
them  imposed  or  removed  by  other  races,  for  all  sorts  of  reasons. 

From  all  these  facts  each  student  may  make  his  own  esti- 
mate of  the  original  mental  differences  of  races,  and  learn  at  least 
the  need  of  more  actual  measurements  of  race  differences  and 


68  Educational  Psychology 

of  intelligence  in  interpreting  them.  My  own  estimate  is  that 
greater  differences  will  be  found  in  the  case  of  the  so-called 
"higher"  traits,  such  as  the  capacity  to  associate  and  to 
analyze,  thinking  with  parts  or  elements,  and  originality,  than 
in  the  case  of  the  sensory  and  sensori-motor  traits,  but  that 
there  will  still  be  very  great  overlapping.  Calling  the  dif- 
ference between  the  original  capacity  of  the  lowest  congenital 
idiot  and  that  of  the  average  modern  European  loo,  I  should 
expect  the  average  deviation  of  one  pure  race*  from  another 
in  original  capacity  to  be  below  lo  and  above  i,  and  the  dif- 
ference between  the  central  tendencies  of  the  most  and  the  least 
gifted  races  to  be  below  50  and  above  10.  I  should  consider  3 
and  25  as  reasonable  guesses  for  the  two  differences. 

Even  if  the  differences  were  far  larger  than  these,  the  prac- 
tical precept  for  education  would  remain  unchanged.  It  is,  of 
course,  that  selection  by  race  of  original  natures  to  be  educated 
is  nowhere  nearly  as  effective  as  selection  of  the  superior  indi- 
viduals regardless  of  race.  There  is  much  overlapping  and  the 
differences  in  original  nature  within  the  same  race  are,  except 
in  extreme  cases,  many  times  as  great  as  the  differences  between 
races  as  wholes. 

*Defining  a  pure  race  arbitrarily  as  one  whose  ancestry  has  less  than 
I  per  cent  of  community  with  that  of  any  other  race  for  at  least  20 
generations  back. 


CHAPTER  V 
The  Influence  of  Immediate  Ancestry  or  Family 

There  is  possibly  even  less  agreement  about  the  amount  of 
influence  of  immediate  ancestry  or  '  family '  than  about  that  of 
remote  ancestry  or  race.  This  is  the  more  to  be  regretted  because 
all  the  social  sciences  and  especially  education  need  as  a  starting 
point  precise  knowledge  of  the  differences  in  original  mental  make- 
up within  the  human  species  and  of  their  j-elation  to  immediate 
ancestry. 

The  problem  naturally  resolves  itself  into  two, — the  measure- 
ment of  the  resemblance  of  individuals  of  like  ancestry  and  the 
subtraction  of  a  proper  allowance  for  their  likeness  in  training. 
Or,  more  exactly,  we  have  to  measure  the  amount  by  which  the 
likeness  of  individuals  of  like  ancestry  surpasses  the  likeness 
of  individuals  of  different  ancestry,  and  subtract  from  it  the 
amount  due  to  their  greater  likeness  in  training  than  that 
found  in  the  case  of  individuals  of  different  ancestry.  Measure- 
ments of  the  greater  differences  of  wwrelated  individuals  with  an 
allowance  for  the  greater  differences  in  their  training  would  serve 
the  same  end.  But  the  effect  of  differences  in  ancestry  in  pro- 
ducing differences  in  intellect  and  character  is  more  easily  meas- 
ured by  the  effect  of  similarity  or  identity  in  ancestry  in  decreas- 
ing such  differences.  The  facts  to  be  considered  are  then  meas- 
urements of  resemblance  and  allowance  for  like  training. 

The  Variability  of  Individuals  of  the  Same  Sex  and  Ancestry 

Resemblance,  not  repetition,  is  to  be  measured.  To  say  that 
a  man's  original  nature  depends  upon  his  ancestry  does  not  mean 
that  it  is  an  exact  facsimile  of  any  one  or  any  combination  of  his 
ancestors.  There  is  no  reason  to  believe  that  four  sons  of  the 
same  parents  and  consequently  of  the  same  total  ancestry  will 
have  the  same  original  natures.     Indeed  we  know  they  will  not, 

(60) 


70  Educational  Psychology 

save  by  chance.  For  twins  who  have  presumably  in  some  cases 
identical  or  nearly  identical  antenatal  influences  and  nurture  may 
vary  widely  in  both  physical  and  mental  traits.  What  ancestry 
does  is  to  reduce  the  variability  of  the  offspring  and  determine  the 
point  about  Avhich  they  do  vary. 

Take,  for  instance,  the  capacity  to  form  intelligent  habits  or 
associations  amongst  sense  impressions,  ideas  and  acts.  The  num- 
ber of  associations  between  situation  and  act,  the  number,  that 
is,  of  things  an  animal  can  do  in  response  to  the  multitude  of 
conditions  of  life,  varies  tremendously  throughout  the  animal 
kingdom.  The  free  swimming  protozoa  studied  by  Professor 
Jennings  had  in  addition  to  the  common  physiological  functions 
hardly  more  than  a  single  habit.  The  sum  of  the  life  of  Para- 
moecium  is  to  eat,  breathe,  digest,  form  tissues,  excrete,  reproduce, 
move  along  in  a  steady  way,  and  when  passing  from  certain  media 
into  others  to  stop,  back,  turn  to  the  aboral  side  and  move  along 
again  as  before.  At  the  other  extreme  is  a  cultivated  human  being 
whose  toilet,  table  manners,  games,  speech,  reading,  business,  etc., 
involve  hundreds  of  thousands  of  associative  habits. 

If  now  we  take  a  thousand  descendants  of  human  beings  and 
count  up  the  number  of  associative  habits  displayed  by  each  we 
shall  of  course  find  a  great  variability.  Some  of  our  thousand 
human  offspring  will  learn  fewer  things  than  some  dogs  and 
cats.  Some  of  them  may  learn  many  more  than  any  of  the 
parents  from  whom  they  sprang.  But  on  the  whole  the  offspring 
of  human  beings  will  vary  about  the  human  average  instead  of 
about  the  general  animal  average,  and  the  average  deviation  of  the 
human  group  will  be  far  less  than  that  of  the  whole  animal 
kingdom. 

To  illustrate  again,  the  children  of  parents  who  are,  say,  3 
inches  above  the  average  of  the  general  population  in  stature  will 
vary  not  about  the  general  average,  but  about  a  point  2  inches 
above  it ;  and  will  differ  one  from  another  only  about  ten  seven- 
teenths as  much  as  one  adult  of  the  general  population  differs 
from  another.* 

Immediate  ancestry  will  then,  when  influential,  cause  children 
to  deviate  from  the  general  average  toward  the  condition  of  their 

*  This  illustration  is  based  on  the  data  reported  by  Galton  in  Natural 
Inheritance. 


The  Influence  of  Immediate  Ancestry  or  Family  yi 

parents  and  to  vary  less  among  themselves  than  would  the  same 
number  of  unrelated  individuals. 

It  might  seem  at  first  sight  that  two  individuals  of  the  same 
sex,  race  and  parentage,  two  brothers  or  two  sisters,  should,  if 
ancestry  counted  at  all,  have  identical  original  natures  and  differ 
only  in  as  far  as  different  environmental  forces  affect  them. 
Common  observation^hows  this  to  be  false,  but  common  thinking 
does  not  always  or  often  understand  that  it  is  false  just  because 
immediate  ancestry  does  count.  If  ancestry  did  not  count,  either 
all  men  would  by  original  nature  be  identical,  or  the  variations 
among  them  would  all  be  miracles.  If  ancestry  did  not  count, 
two  brothers  might  well  be  identical  in  original  nature,  for  all 
human  males  might  be.  But  if  ancestry  is  a  force,  it  is  certainly 
a  variable  one,  the  germs  produced  by  any  one  parent  being  some- 
what different  among  themselves  for  the  same  reason  that  the 
germs  produced  by  all  parents  together  vary  still  more.  If  the 
germs  differ  at  all,  the  differences  are  likely  to  be  less  amongst 
the  germs  of  any  one  human  being  than  amongst  an  equal  number 
from  all  men,  but  the  differences  are  not  at  all  likely  to  be  reduced 
to  zero. 

In  all  thought  of  inheritance,  physical  or  mental,  one  should 
always  remember  that  children  spring,  not  from  their  parents' 
bodies  and  minds,  but  from  the  germs  of  those  parents.  The 
qualities  of  the  germs  of  a  man  are  what  we  should  know  in 
order  to  prophesy  directly  the  traits  of  his  children.  One  quality 
these  germs  surely  possess.  They  are  variable.  Discarding  syn- 
tax and  elegance  for  emphasis,  we  may  say  that  the  germs  of  a 
six-foot  man  include  some  six-feet  germs,  some  six-feet-one 
germs,  some  six-feet-two,  some  five-feet-eleven,  some  five-feet- 
ten,  etc.  Each  human  being  gives  to  the  future,  not  himself,  but 
a  variable  group  of  germs.  This  hypothesis  of  the  variability  of 
the  germs  explains  the  fact  that  short  parents  may  have  tall  sons ; 
gifted  parents,  stupid  sons ;  the  same  parents,  unlike  sons. 

Methods  of  Measuring  Resemblance  in  Mental  Traits 

In  order  to  understand  the  measurements  of  the  resemblance 
of  related  individuals  which  are  to  be  reported  in  this  chapter, 
it  will  be  helpful  to  consider  one  sample  case  in  some  detail. 
Table  8  gives  (in  columns  i  and  2)  the  facts  concerning  the 
cephalic  index  (width  of  head  divided  by  length  of  head)  in  the 


^2  Educational  Psychology 

case  of  78  individuals,  comprising  39  pairs  of  twins.  Columns  3 
and  4  give  the  same  facts  expressed  as  deviations  from  .81,  which 
is  the  central  tendency  for  cephalic  index  in  the  population  from 
which  these  children  were  chosen.  That  is,  the  first  four  columns 
of  the  first  line  of  the  table  read, — "  Of  two  twins  one  had  a 
cephalic  index  of  ,788,  the  other  of  .790;  one  was  .025  below* 
the  average  of  the  population,  the  other  was  .023  below  it." 

Column  5  gives  the  difference  between  the  indices  of  the  twins 
in  each  of  the  39  pairs.  Column  6  gives  the  algebraic  product  of 
the  deviations  of  the  indices  of  the  twins  from  the  average  cephalic 
index  of  the  population. 

Consider  first  column  5,  in  connection  with  this  question,  "  How 
much  smaller  is  the  difference  between  twin  and  twin  of  a  pair 
than  that  between  two  children  in  general  ?  "  Column  5  gives  the 
former  differences ;  the  latter  can  be  got  by  getting  all  the  differ- 
ences between  each  child  and  the  other  seventy-seven.  Thus  we 
find  individual  i  differing  from  loi,  2,  102,  5,  105,  6,  106,  etc., 
by  2,  8,  15,  18,  24,  28,  38,  61,  49,  etc.  Individual  loi  differs 
from  2,  102,  5,  105,  6,  106,  etc.,  by  10,  13,  16,  22,  26,  36,  59,  47, 
etc.  Individual  2  differs  from  102,  5,  105,  6,  106,  etc.,  by  7,  16, 
32,  36,  40,  etc.  The  differences  between  twin  and  twin  range 
from  o  to  57,  averaging  18.  If  the  reader  should  figure  out  the 
difference  between  two  children  of  the  same  age  but  not  of  the 
same  family,  he  would  find  it  to  range  from  o  to  174  or  more 
and  to  average  about  40.  This  is  the  simplest  method  of  meas- 
uring the  degree  to  which  individuals  of  like  ancestry  resemble 
one  another  more  than  individuals  of  unlike  ancestry  do.  But  it 
is  for  many  reasons  not  the  most  convenient  way  and  is  rarely 
used. 

Consider  now  columns  3  and  4  in  connection  with  the  question, 
"  How  much  oftener  are  the  twins  both  short-wide-headed  or 
both  long-narrow-headed  than  are  two  children  in  general  ? " 
Both  twins  are  thus  alike  (that  is  both  deviate  from  the  average 
in  the  same  direction)  in  32  out  of  the  39  pairs,  or  in  82  per 
cent  of  the  cases.  Two  children  taken  at  random  will  be  thus 
alike  in  50  per  cent  of  the  cases.  '  Greater  than  jo  per  cent  fre- 
quency of  deviation  of  related  individuals  in  the  same  direction 
from  the  central  tendency/  is  another  simple  measure  of  their 
greater  resemblance  than  that  of  the  non-related  individuals. 

*  Below  meaning  more  long-narrow-headed,  or  "dolichocephalic." 


The  Influence  of  Immediate  Ancestry  or  Family  73 

TABLE  8. 
Resemblances  of  Twins  in  Cephalic  Index. 


0"(N 


Pairs  op 

Twins 


05  A. 


I  and  101 
102 
105 
106 

107 
108 
109 
no 

III 

112 

"3 

116 

117 
118 
119 

120 

121 
123 
124 
125 

126 
127 
128 
129 

130 

132 
134 

135 
136 

137 
138 

140 
141 

143 
144 

145 
147 
150 


9 
10 

II 
12 

13 
16 

17 
18 

19 
20 

21 
23 

24 
25 
26 

27 
28 
29 

30 
31 
32 

34 

35 
36 
37 
38 

40 
41 
43 
44 

45 
47 
50 


788 
780 
796 
816 

849 
853 
777 
801 

745 
804 
823 
765 

778 
836 

839 
761 

786 
806 
778 
826 

802 
834 
763 
827 

814 

789 
819 
758 

817 
786 
817 
827 

850 
838 
783 
785 

899 
832 
836 


^2 


790 

773 
812 
826 

837 
859 
766 
770 

738 
773 
859 
763 

788 
836 

797 
768 

783 
831 
784 
850 

793 
839 
817 

843 

827 

773 
828 

725 

780 
836 
830 
846 

793 
846 
786 
826 

856 
828 


SB?? 


-25 

-2,3 

-17 

3 

36 

40 

-36 

-12 

-68 

-  9 
10 

-48 

-35 
23 
26 

-52 

-27 
—7 
-35 

13 
-II 

21 
-50 

13 

I 

-24 
6 

-55 

4 

-27 

4 

13 

37 

25 

-30 

-28 

86 
i8 
23 


.2  o  ^ 


—  23 
—40 

—  I 
13 

24 
46 

—47 

—43 

—75 

—40 

46 

—50 

—25 
23 

—  16 

—45 

—30 
18 

—29 

37 

— 20 

26 

4 

30 

14 
—40 

15 


23 
17 
31 

-20 
31 

-27 
13 

43 
14 
25 


2 

7 
16 
10 


31 

7 
31 
36 

2 

10 
o 

42 
7 

3 

25 

6 

24 

9 

5 

54 

17 

13 
16 

9 

33 

37 
50 
13 
18 

57 
6 

3 
41 

43 
4 
2 


o  :-  O 


575 
1320 

17 
39 

864 
1840 
1692 

516 

5100 
360 
460 

2400 

875 
529 

2340 
810 

1015 
481 

220 
546 

390 

14 

960 

90 

4840 


68 
403 


775 
810 


3698 
252 
575 


—416 


-126 


-132 
-621 


-740 
-364 


74  Educational  Psychology 

Consider  now  columns  3  and  4  in  connection  with  this  ques- 
tion, "  What  is  the  ratio  of  one  twin's  deviation  from  the  C.  T.* 
to  that  of  his  mate  ?  "  We  find  these  78  ratios,  using  the  ratio 
of  I's  deviation  to  loi's  and  also  loi's  to  I's  and  so  on,  to  be 
11.  If.  ft.  If.  ¥.  TT.  A.  V-.  etc.,  fourteen  of  them  being  minus 
quantities.  The  central  tendency  (Median)  of  these  ratios  is  .87. 
Now  if  twin  and  twin  always  possessed  perfect  resemblance, — 
if  the  two  indices  of  each  pair  were  alike, — these  ratios  would 
each  be  I.  If  we  take  the  ratio  of  any  person's  deviation  from 
the  C.  T.  to  that  of  any  other  person  regardless  of  blood  rela- 
tionship, there  will  be  as  many  minus  quantities  as  plus  quantities 
and  the  median  of  the  ratios  will  be  o.  The  median  of  the  ratios, 
each  of  the  deviation  of  one  member  of  a  related  pair  from  the 
central  tendency  of  the  whole  group  to  the  similar  deviation  of 
the  other  member,  is  an  important  measure  of  resemblance. 
When  it  is  o,  it  means  no  greater  resemblance  than  one  of  the 
group  bears  to  another  taken  at  random.  When  it  is  i.oo  it 
means  perfect  resemblance  or  identity.  When  it  is  .5  it  means 
a  resemblance  halfway  between  perfect  identity  and  that  found 
between  any  two  persons  of  the  group  taken  at  random.  This 
is  for  many  reasons  the  most  serviceable  measure  of  resemblance 
between  individuals,  and  it,  or  a  measure  that  may  for  the  pur- 
poses of  this  chapter  be  regarded  as  the  same  as  it,  will  be  used 
in  reporting  the  resemblances  found  by  various  students  of  hered- 
ity. The  figures,  ranging  from  o  to  i.oo,  called  Coefficients  of 
Correlation,  designated  by  the  symbol  R,  and  used  to  measure 
resemblance,  are  to  be  thought  of  as  expressing  the  central  tend- 
encies (medians)  of  series  of  ratios,  such  as  the  series  of  78  ratios 
afforded  by  the  deviation-measures  of  Table  8. 

The  central  tendency  of  a  series  of  ratios  may  however  be  cal- 
culated in  another  form,  the  so-called  Pearson  coefficient  of  cor- 
relation or  resemblance,  which  is  somewhat  less  easy  to  describe. 
Consider  column  6  in  connection  with  the  question,  "What  would 
these  products  be  if  the  two  twins  were  identical  in  the  case  of 
every  pair?"  In  the  first  pair  the  product  is  575.  If  the  twins 
were  identical  it  would  be  either  625  (25  times  25)  or  529  (23 
times  23)  according  as  the  second  twin  was  to  be  identical  with 
the  first  or  the  first  with  the  second.     In  the  second  pair  the 

*C.  T.  is  used  here  and  later  as  an  abbreviation  for  central  tendency. 


The  Influence  of  Immediate  Ancestry  or  Family  75 

product  is  1320.  With  perfect  resemblance  it  would  be  1089  or 
1600.  In  the  third  pair  it  is  17,  With  perfect  resemblance  it 
would  be  189  or  I.  In  the  fourth  the  corresponding-  products 
are  39  and  9  or  169.     In  the  fifth  pair  they  are  864  and  1296  or 

576. 

Consider  now  the  sum  of  the  five  products  as  it  is  (2815),  and 
as  it  would  be  with  perfect  resemblance  (3208  or  2875).  Con- 
sider what  the  sum  of  the  products  would  be  with  no  greater 
resemblance  than  that  found  between  any  one  of  the  group  and 
any  other  one  taken  at  random.  A  plus  deviation  would  then  go 
with  a  minus  deviation  as  often  as  with  a  plus ;  in  the  long  run 
as  many  of  the  algebraic  products  would  be  negative  as  positive ; 
and  their  sum  would  be  o.  The  proportion  which  the  sum  of 
the  products  of  the  related  deviations  is  of  what  that  sum  would 
be  with  perfect  resemblance  is  thus  a  measure  of  the  amount  of 
resemblance. 

This  proportion^  — /  ^^         ^^  ^        ^^  ^  ^ 

\     (x,2+X,2+X3^...X„2)(y^2+y,^2+y.^2   _..y^2) 

2'  X.  y 

°^l/^^2.Jy2 

Xj,  X2,  Xg,  etc.  being  the  deviations  of  the  first  members  of  the 
related  pairs,  and  yi,y2.y3,  etc.  being  the  corresponding  deviations 
of  the  second  members  of  the  related  pairs.  2"=  '  sum  of  the 
series  of. ' 

Thus  for  the  5  pairs  above 

2815 


1    3208  .  2875 


2  X   y 

When  —  -  =  1 ,  resemblance  is  perfect. 

2"  X  V 
When  —  ^  =  0,    there    is  no    greater  resemblance  than 

Vl^.Iy' 
exists  between  the  members  of  the  group  taken  at  random.  A 
resemblance  calculated  by  this,  the  so-called  product-moment 
method,  devised  by  Karl  Pearson,  may  for  our  purposes  be  con- 
sidered as  meaning  the  same  thing-  as  the  median  of  the  series  of 
ratios  previously  described. 

If  the  reader  still  feels  a  certain  insecurity  and  unreality  about 
the  values  of  R  =  o,  R  =  .i,  R  =  .2,  R=.35,  R=.75.  R=-9, 
and  the  like,  he  can  make  these  coefficients  of  resemblance  or 


yd  Educational  Psychology 

correlation  living  realities  by  artificially  so  pairing  the  following 
series  as  to  get  from  them  various  values  of  R,  either  as  R=  the 

median  of  the  — -f^-  ratios  or  as  R  = 


y        X  VlxKIy^ 

Series  i.     (x) +  i +  i  +  i  +  i +3+3+3 +  5 +  7  +  ii  -  i  — i  —  i  — i - 

3-3-3-5-7-11 
Series  2.     (y)  +  i  +  i  +  i  +  i+3+3+3  +  5  +  7  +  ii-i-i  —  i  —  i  — 

3-3-3-5-7-11 
Thus,    pairing    them    in    order,     R=  i,     while    pairing    them 

(  +  1+3)  (+1-1)  (+1  +  1)  (  +  1-1)  (  +  3+3)  (  +  3  +  5)  (  +  3-1) 
(  +  5  +  1)  (  +  7  + II)  (  +  11  + I)  (-1  +  7)  (-1-3)  (-1-5)  (-1+3) 
(-3  +  1)  (-3-1)  (-3-7)  (-5-11)  (-7-3)  (-ii-3),R=-54. 
It  will  be  specially  useful  to  pair  them  so  as  to  get  R== —  i,  so 
as  to  get  R  =  o,  so  as  to  get  R  =  about  .2,  and  so  as  to  get 
R  =  about  .8. 

The  Influence  of  Ancestry  on  Physical  Traits 

Before  describing  the  similarities  of  closely  related  individuals 
in  mental  traits  I  shall  present  the  results  of  studies  in  the  case 
of  some  physical  traits  which  will  prove  that  heredity  is  a  vera 
causa,  since,  in  them,  similarity  of  training  is  out  of  the  question 
as  a  cause  of  the  similarities  found. 

The  coefficient  of  correlation  between  brothers  in  the  color  of 
the  eyes  is,  according  to  Pearson,  .52.  But  parents  could  not,  if 
they  would,  exert  any  environmental  influence  upon  the  color  of 
their  children's  eyes.  The  fraternal  resemblance  must  be  due  to 
the  resemblance  in  ancestry. 

In  height  Pearson  finds  the  coefficient  of  correlation  between 
father  and  son  to  be  .3,  and  that  between  brother  and  brother  to 
be  .5.  In  other  words,  a  son,  on  the  average,  deviates  from  the 
general  trend  of  the  population  by  .3  the  amount  of  his  father's 
deviation,  a  brother  by  .5  the  amount  of  his  brother's.  Now  no 
one  can  imagine  that  tall  fathers  try  especially  to  make  their  sons 
tall.  Nor  will  the  class  '  men  two  inches  above  the  average 
height '  feed  their  children  any  more  than  men  one  inch  above  it. 

The  coefficient  of  fraternal  correlation  in  the  case  of  the 
cephalic  index  (ratio  of  width  to  length  of  head)  is,  according  to 
Pearson,  .49.     Here  it  is  utterly  incredible  that  fathers  do  any- 


The  Influence  of  Immediate  Ancestry  or  Family  "jy 

thing  to  their  children  that  would  tend  to  produce  in  them  similar 
indices. 

Finally  take  color  of  hair.  Fraternal  correlation  is,  according 
to  Pearson,  .55.  Here  again  home  influence  could  not  cause  one 
whit  of  the  resemblance. 

Immediate  ancestry  can  and  does,  apart  from  any  other  force, 
cause  in  whole  or  in  part  the  abmodality,  or  deviation  from  the  C. 
T.  of  his  race,  of  an  individual  in  the  case  of  stature,  cephalic 
index  and  eye  color.  There  is  no  reason  to  suppose  that  the  brain 
is  less  influenced  by  ancestry  than  are  the  tissues  that  cause 
height,  or  the  shape  of  the  skull  bones  that  causes  cephalic  index, 
or  the  deposits  of  pigment  that  cause  eye  color.  Immediate 
ancestry  is  thus  a  probable  cause  for  original  mental  nature.  And 
when  there  is  doubt  as  to  the  choice  between  it  and  the  environ^ 
ment  as  the  cause  of  differences  in  mental  traits  of  individuals 
at  any  age,  it  must  not  be  forgotten  that  the  influence  of  the 
latter  is,  after  all,  largely  a  matter  of  speculation,  while  the  influ- 
ence of  ancestry  is  in  physical  traits  a  demonstrated  fact. 

Measurements  of  the  Influence  of  Ancestry  on  Mental  Traits 

Deafness  may  be  considered  a  physical  trait  because  it  is  due 
to  physical  causes,  but  so  are  all  mental  traits.  The  real  differ- 
ence is  that  we  know  more  about  the  causes  in  the  one  case  than 
in  the  others.  The  manifestation  and  results  of  deafness  are  cer- 
tainly mental  traits. 

The  brother  or  sister  of  a  person  born  deaf  is  found  to  be 
deaf  in  245  cases  out  of  1,000,  almost  one  case  out  of  four.  The 
number  of  deaf  persons  amongst  1,000  brothers  and  sisters  of 
hearing  individuals  is  not  known  exactly,  but  it  is  certainly  less 
than  I,  probably  much  less.  That  is,  a  person  of  the  same  ances- 
try as  a  congenitally  deaf  person  is  at  least  245  (probably  many 
more)  times  as  likely  to  be  deaf  as  a  person  of  the  same  ancestry 
as  a  hearing  person.  The  child  of  two  parents  both  of  whom 
were  born  deaf  is  at  least  259  (probably  many  more)  times  as 
likely  to  be  deaf  as  the  child  of  two  hearing  parents  [Fay,  '98, 
p.  49].  In  this  case,  as  with  the  physical  traits  described,  there 
is  no  reason  to  impute  any  efficacy  to  training.  Parents  born 
deaf  would  take  pains  to  prevent  deafness  in  their  children. 

Mr.  E.  L.  Earle  [03]  measured  the  spelling  abilities  of  some 


78  Educational  Psychology 

600  children  in  the  St.  Xavier  school  in  New  York  by  careful 
tests.  As  the  children  in  this  school  commonly  enter  at  a  very 
early  age,  and  as  the  staff  and  methods  of  teaching  remain  very 
constant,  we  have  in  the  case  of  the  180  pairs  of  brothers  and 
sisters  included  in  the  600  children  closely  similar  school  train- 
ing. Mr.  Earle  measured  the  ability  of  any  individual  by  his 
deviation  from  the  average  for  his  grade  and  sex  and  found  the 
coefficient  of  correlation  between  children  of  the  same  family 
to  be  .50.  That  is,  any  individual  is  on  the  average  50  per  cent 
as  much  above  or  below  the  average  for  his  age  and  sex  as  his 
brother  or  sister. 

Similarities  in  home  training  might  theoretically  account  for 
this,  but  any  one  experienced  in  teaching  will  hesitate  to  attribute 
much  efficacy  to  such  similarities.  Bad  spellers  remain  bad 
spellers  though  their  teachers  change.  Moreover,  Dr.  J.  M.  Rice 
in  his  exhaustive  study  of  spelling  ability  ['97]  found  little  or 
no  relationship  between  good  spelling  and  any  one  of  the  popular 
methods,  and  little  or  none  between  poor  spelling  and  foreign 
parentage.  Yet  the  training  of  a  home  where  the  parents  do 
not  read  or  spell  the  language  well  must  be  a  home  of  relatively 
poor  training  for  spelling.  Cornman's  more  careful  study  of 
spelling  ['01]  supports  the  view  that  ability  to  spell  is  little 
influenced  by  such  differences  in  school  or  home  training  as 
commonly  exist. 

These  facts  make  it  almost  certain  that  immediate  ancestry  does 
count  somewhat  in  producing  the  likenesses  and  differences  found 
amongst  men  in  mental  traits.  In  the  measurements  now  to  be 
reported,  the  influence  of  family  training  enters  as  a  more  prob- 
able alternative  cause  of  the  resemblance.  I  shall  in  each  case 
give  the  measurement  of  resemblance  made  and  the  allowance 
for  likeness  in  home  training  suggested  by  the  author. 

The  first  serious  study  of  the  inheritance  of  mental  traits  was 
made  in  the  6o's  by  Francis  Galton  and  reported  in  Hereditary 
Genius  ['69,  '92].  He  examined  carefully  the  careers  of  the 
relatives  of  977  men  each  of  whom  would  rank  as  one  man  in 
four  thousand  for  eminent  intellectual  gifts.  They  had  relatives 
of  that  degree  of  eminence  as  follows : — fathers  89,  brothers  1 14, 
sons  129,  all  three  together  332 ;  grandfathers  52,  grandsons  37, 
uncles  53,  nephews  61,  all  four  together  203.  The  probable 
numbers  of  relatives  of  that  degree  of  eminence  for  977  average 


The  Influence  of  Immediate  Ancestry  or  Family  79 

men  are  as  follows : — fathers,  brothers,  and  sons  together,  i  ; 
grandfathers,  grandsons,  uncles  and  nephews  all  together,  3. 
Galton  argues  that  the  training  due  to  the  possession  of  eminent 
relatives  can  not  have  been  the  cause  of  this  superior  chance  of 
eminence  in  the  relatives  of  gifted  literary  men  and  artists. 

He  says :  "To  recapitulate :  I  have  endeavored  to  show  in 
respect  to  literary  and  artistic  eminence — 

1.  That  men  who  are  gifted  with  high  abilities — even  men  of 
class  E — easily  rise  through  all  the  obstacles  caused  by  inferiority 
of  social  rank. 

2.  Countries  where  there  are  fewer  hindrances  than  in  England, 
to  a  poor  man  rising  in  life,  produce  a  much  larger  proportion  of 
persons  of  culture,  but  not  of  what  I  call  eminent  men.  (England 
and  America  are  taken  as  illustration.) 

3.  ]\Ien  who  are  largely  aided  by  social  advantages  are  unable  to 
achieve  eminence,  unless  they  are  endowed  with  high  natural  gifts." 

Galton  demonstrates  that  the  adopted  sons  of  popes  do  not 
approach  equality  in  eminence  with  the  real  sons  of  gifted  men. 
He  so  orders  his  studies  of  men  eminent  in  other  fields  as  to  leave 
very  slight  basis  for  one  who  argues  that  training  and  opportunity 
rather  than  birth  caused  the  eminence  attained.  Finally,  Gal- 
ton's  own  opinion,  that  of  an  eminently  fair  scientific  man  based 
upon  an  extensive  study  of  individual  biographies,  may  safely  be 
taken  with  a  very  slight  discount.  He  says : — 'T  feel  convinced 
that  no  man  can  achieve  a  very  high  reputation  without  being 
gifted  with  very  high  abilities."  , 

The  historic  importance  of  Galton's  Hereditary  Genius,  the  i 
originality  and  ingenuity  of  its  author  and  its  substantial  results,  \ 
should  make  his  book  the  first  to  be  read  by  every  student  of  s 
mental  inheritance. 

Loewenfeld  ['03]  confirms  Galton's  estimate  of  the  resemblance 
in  intellect  and  energy  amongst  descendants  from  similar  near 
ancestry. 

In  1889  Galton  published  his  Natural  Inheritance,  the  re- 
sults of  more  precise  studies  *  of  resemblances  amongst  related 
individuals  in  stature,  eye  color,  the  artistic  faculty  and  diseases. 
He  found  the  resemblance  between  parents  and  their  children 
in  the  mental  trait  studied  (artistic  faculty)  to  be  a  httle  greater 

*These  studies  were  reported  in  various  memoirs  from  18" i  to  1887. 


8o  Educational  Psychology 

than  in  the  case  of  stature.  The  essential  facts  from  which  this 
inference  is  drawn  are  that  in  30  famiHes  where  both  parents 
were  artistic  64  per  cent  of  the  children  were  so,  whereas  in  150 
families  where  neither  parent  was  artistic  only  21  per  cent  of  the 
children  were  so  ['89,  p.  218].  No  attempt  is  made  to  divide  the 
causation  of  this  resemblance  between  birth  and  training. 

Pearson  ['04]  secured  ratings  by  teachers  of  about  2,000  pairs 
of  siblings  with  respect  to  the  following  traits : — ability,  vivacity, 
conscientiousness,  popularity,  temper,  introspection  or  self-con- 
sciousness, assertiveness  and  handwriting.  In  ability  and  hand- 
writing the  measure  was  a  grade  from  one  to  six  according  to 
ability;  in  temper  from  one  to  three.  In  the  other  traits  the 
individual  was  put  into  an  upper  or  a  lower  class.  Such  material 
is  not  well  suited  for  measuring  resemblance,  chiefly  for  two 
reasons.  First,  the  measurements  are  very  coarsely  made,  and 
so  have  a  large  chance  inaccuracy.  A  slight  prejudice  or  ignor- 
ance in  the  teacher  making  the  measurement  may  put  a  boy  who 
is  really  above  the  average  in  one  of  these  traits  below  it.  If 
errors  of  judgment  displace  a  boy  on  the  scale  at  all,  they  will 
alter  his  position  by  half  the  total  scale  in  five  of  these  traits,  by 
a  third  of  the  scale  in  one  and  by  a  sixth  in  the  other.  Such 
chance  errors  are  sure  to  occur.  Their  effect  is  to  make  the 
resemblances  obtained  from  the  teachers'  ratings  lower  than  the 
real  resemblances.  Spearman  ['04,  p.  97  &.]  has  estimated  that 
if  these  teachers'  ratings  suffer  from  such  chance  errors  as  he 
himself  finds  in  such  ratings,  the  obtained  resemblances  (which 
are  about  .5)  are  very  much  too  low,  the  real  resemblances 
required  to  produce  a  measurement  of  R  =  .5  when  '  attenuated ' 
by  the  teachers'  chance  errors,  being  over  .8.  Pearson  denies  that 
the  teachers'  ratings  were  thus  inaccurate,  claiming  that  they 
displaced  a  pupil  from  his  proper  class  only  rarely.  Spearman 
possibly  overestimates  the  chance  errors  of  a  teacher's  judgment 
of  the  intellect  or  character  of  a  boy  well  known  to  him,  but 
Pearson  certainly  underestimates  them,  when  he  makes  no  allow- 
ance at  all  for  them. 

He  measured  them  only  in  the  case  of  '  ability,'  which  would 
be  the  easiest  of  these  traits  for  a  teacher  to  grade  accurately,  and 
which  was  graded  by  a  six-step  scale.  Three  teachers  in  a  school 
graded  the  same  pupils  for  him  *  without  consultation  among 

*This  being  done  for  some  150  boys  and  girls  in  all,  distributed  in  six 
schools. 


The  Influence  of  Immediate  Ancestry  or  Family 


themselves,  with  the  result,  he  writes,  that  '  the  agreement  in 
classification  was  complete  in  more  than  80  per  cent  of  cases  and 
only  differed  by  as  much  as  two  classes  in  about  5  per  cent  of 
cases,'  ['04,  p.  161.]  But  such  gradings  are  not  really  indepen- 
dent, if  the  pupils  are  talked  about  by  their  teachers. 


J* 


Ja- 


FiG.  24.     The  real  un- 
likeness  of  Jo.  and  Ja. 


Fig.  25.  The  specious  likeness  of  Jo.  and  Ja. 
when  they  are  rated  by  teachers  who  place  the 
dividing-line  between  self-conscious  and  unself- 
conscious  too  low  or  too  high. 


The  second  error  acts  in  the  reverse  direction.  Any  teacher 
has  his  own  idea  of  '  quiet,'  '  noisy,'  '  keen'  in  conscientiousness 
or  '  dull '  in  conscientiousness,  and  the  like.  Whether  he  shall 
rate  a  boy  as  '  self-conscious  '  or  '  unself-conscious  '  depends  only 
in  part  on  what  the  boy's  nature  is.  In  part  it  depends  on  where 
the  teacher  draws  the  line  between  being  self-conscious  and  being 
unself-conscious.  Suppose,  for  instance,  John  and  James  to  be 
really  at  points  Jo  and  Ja  on  the  scale  for  self-consciousness 
represented  in  Fig.  24,  and  suppose  the  average  self-consciousness 


82  Educational  Psychology 

of  English  boys  to  be  really  at  point  Av.  on  this  scale.  Consider 
now  ten  teachers  each  of  whom  is  asked,  "  Is  John  self-conscious 
or  unself-conscious  ?  "  Each  of  them  is  in  total  ignorance  of  the 
position  of  the  dividing  point,  every  point  above  which  should  be 
rated  '  self-conscious  '  and  every  point  below  which  should  be 
rated  '  unself-conscious.'  Each  of  them  makes  his  own  dividing 
point.  These  divisions  will  vary.  How  much  they  will  vary  is 
not  known.  Fig.  25  gives  an  arbitrary  estimate  of  ten  as 
an  illustration.  Now  John  and  James,  when  rated  by  these  ten 
subjective  scales,  seem  alike  in  four  cases  out  of  ten,  though  they 
are  really  not  in  this  sense  alike,  one  being  really  above  and  the 
other  below  the  real  dividing  line.  Now,  in  general,  any  differ- 
ence in  judges  in  making  the  subjective  divisions  of  the  scales 
whereby  they  rate  the  boys  will  lead  the  judges  to  rate  boys  who 
are  really  different  as  alike  oftener  than  it  will  lead  them  to 
rate  boys  who  are  really  alike  as  different.  For  there  are  many 
more  boys  near  the  dividing  line  than  at  the  extremes,  and  the 
brothers  of  a  pair  are  usually  rated  by  the  same  judge.  Hence 
the  resemblances  as  calculated  from  these  teachers'  ratings  are, 
in  so  far  forth,  greater  than  the  real  resemblances.  How  much 
greater  is  not  known,  since  the  amount  of  difference  between  the 
subjective  and  the  real  dividing  point  is  not  known.  The  error 
would  probably  be  greater  in  the  case  of  conscientiousness,  self- 
consciousness  and  shyness,  where  subjective  standards  prob- 
ably vary  very  much,  than  in  the  case  of  intelligence  or  popularity. 
The  average  resemblance  of  .52  obtained  by  Pearson  would  thus 
be  raised  if  one  error  had  been  avoided,  and  lowered  if  a  second 
error  had  been  avoided.  I  judge  that  roughly  on  the  whole  the 
two  errors  would  somewhat  nearly  balance.  Just  what  would 
happen  to  each  of  the  particular  resemblances  if  accurate  original 
measurements  had  been  secured,  cannot  be  more  than  guessed. 
Pearson's  obtained  measures  were  ['04,  p.  155]  : — 


Brother  a 

Brothers        Sisters 

Sister 

Vivacity 

47 

43 

■49 

Self-assertiveness 

■53 

44 

•52 

Introspection 

59 

47 

■63 

Popularity 

50 

57 

•49 

Conscientiousness 

59 

64 

■63 

Temper 

■51 

49 

■51 

Ability 

.46 

47 

■44 

Handwriting 

53 

56 

.48 

Average 

52 

51 

•52 

The  Influence  of  Immediate  Ancestry  or  Family  83 

A  third  criticism  of  Professor  Pearson's  measurements  might 
be  that  the  teachers  who  reported  cases  of  brothers  tended  to 
select  brothers  whose  hkeness  was  notable  and  to  grade  them  alike 
oftener  than  the  facts  warranted.  It  is  true  that  if  you  seek 
information  from  people  without  special  training  in  the  field  of 
science  concerned,  the  answers  obtained  are  well-nigh  sure  to 
be  compounds  of  fact  and  prejudice,  but  there  is  apparently  no 
reason  to  believe  that  the  teachers  had,  apart  from  the  directions 
sent  to  them,  any  prejudicial  belief  in  fraternal  similarity. 

In  two  ways  the  directions  for  making  the  judgments  may 
have  tended  to  suggest  the  existence  of  resemblances.  The 
directions  read: — "  i.  The  object  of  this  investigation  is  two- 
fold :     ( I )   To  ascertain  the  degree  of  resemblance,  mental  and 

physical,  between  children  of  the  same  parents 

2.  The  measurements  and  estimates  are  to  be  made  on  (I) 
Pairs  of  brothers  (white  data  paper).  (II)  Pairs  of  sisters  (pink 
data  paper).  (Ill)  Pairs  of  brothers  and  sisters  (blue  data 
paper)."  ['04,  p.  161.]  It  would  have  been  far  better  to  have 
had  all  the  children  in  the  school  rated  each  on  a  sheet  by  himself 
and  to  have  said  nothing  about  the  purpose  for  which  the  meas- 
urements were  to  be  used. 

There  is  one  more  fact  to  be  noted  which  must  lessen  con- 
fidence in  these  measurements  still  further.  Using  just  the  same 
method  of  securing  the  data  as  in  the  cases  discussed.  Professor 
Pearson  gets,  from  ratings  of  athletic  or  non-athletic,  resemblances 
of  .y2  for  brothers,  .75  for  sisters  and  .49  for  brother  and  sister 
['04,  p.  154].  Now  we  know  that  if  these  measurements  are 
free  from  error  in  all  respects  save  the  mere  chance  errors  of 
judgment  of  the  teachers,  the  real  resemblances  must  be  even 
higher  than  .72,  .75  and  .49.  But  so  close  resemblance  as  a  result 
of  original  nature  alone  is  absurd.  There  is  nothing  like  it  else- 
where in  fraternal  resemblances,  save  in  twins.  In  the  case  of 
athletic  power  Professor  Pearson's  figures  surely  measure  the 
dififerences  of  schools  in  devotion  to  athletics  or  the  difTerences 
of  the  judges  as  to  where  the  dividing  line  is  between  athletic 
and  not  athletic,  as  well  as  the  resemblances  of  brothers  and 
sisters  in  original  nature. 

Professor  Pearson  thinks  that  no  allowance  is  due  for  the 
similarities  of  home  training  because  the  resemblances  in  health, 
eye-color,  hair-color  and  five  other  physical  traits   average   .54, 


84  Educational  Psychology 

.53  and  .51  for  the  three  groups  of  pairs.  The  resemblances 
in  these  physical  traits  cannot  be  due  to  the  fact  that  the  brothers 
have  the  same  home  environment,  he  says,  yet  the  resemblances 
are  as  great  as  in  mental  traits.  Professor  Pearson  lays  great 
stress  on  the  exact  equality  of  physical  and  mental  resemblance, 
but  since  his  measures  of  the  latter  are  subject  to  two  important 
sources  of  error,  this  exact  correspondence  is  of  doubtful 
significance. 

Unless  one  is  a  blind  devotee  to  the  irrepressibility  and  unmod- 
ifiability  of  original  mental  nature,  one  cannot  be  contented  with 
the  hypothesis  that  a  boy's  conscientiousness  or  self-consciousness 
is  absolutely  uninfluenced  by  the  family  training  given  to  him. 
Of  intelligence  in  the  sense  of  ability  to  get  knowledge,  rather 
than  amount  of  knowledge  got,  this  might  be  maintained.  But 
to  prove  that  conscientiousness  is  irrespective  of  training  is  to 
prove  too  much.  One  fears  that  Professor  Pearson  may  next 
produce  coefficients  of  correlation  to  show  that  the  political  party 
a  man  joins,  the  place  where  he  lives,  and  the  dialect  he  speaks 
are  matters  of  pure  inheritance  uninfluenced  by  family  training ! 

The  reader  may  at  this  stage  be  in  some  doubt  as  to  precisely 
what  Professor  Pearson's  measurements  give  as  a  probable  simi- 
larity of  brothers'  original  natures.  I  share  this  doubt,  and  from 
estimating  the  different  sources  of  error  can  do  no  more  than 
expect  that  adequate  mental  measurements  with  the  effects  of 
similarity  of  training  eliminated  would  leave  resemblances  of 
from  .3  to  .5. 

Dr.  Frederick  Adams  Woods  has  reported  in  Mental  and 
Moral  Heredity  in  Royalty  ['06],  a  work  which  appeared  first  in 
the  Popular  Science  Monthly  in  1902  and  1903,  measurements 
of  the  resemblances  in  intellect  and  in  morals  of  many  individuals 
chosen  from  the  royal  families  of  Europe.  Dr.  Woods  gave  to 
each  person  of  the  671  studied  a  rating  from  i  to  10  on  a  scale 
for  intellect — i  representing  feeble-mindedness  or  imbecility ;  10 
such  gifts  as  those  of  William  the  Silent,  Frederick  the  Great 
and  Gustavus  Adolphus  ;  and  2,  3,  4,  5,  etc.,  steps  at  equal  intervals 
between,  in  his  opinion.  These  ratings  represented  Dr.  Woods' 
impressions  from  reading  the  statements  of  historians  and  biog- 
raphers about  these  individuals.  He  gave  similar  ratings  for 
morality. 

The  ratings  assigned  by  Dr.  Woods  are,  of  course,  not  accur- 


The  Influence  of  Ininiediate  Ancestry  or  Family  85 

ate.  No  one  man's  ratings  of  nearly  seven  hundred  historical 
personages  could  be.  The  effect  of  this  chance  inaccuracy  would 
be  to  make  all  his  measurements  of  resemblance  lower  than  the 
real  resemblance.  He  may  also  have  erred  from  an  unconscious 
prejudice  by  rating  as  too  much  alike  individuals  who  were  closely 
related.  This  error  would  tend  obviously  to  make  his  estimate 
of  resemblance  too  high.  His  ratings  are  given  in  full  and  so  far 
nobody  has  proved  or  even  suggested  that  they  are  thus  biased. 

There  is  still  another  chance  for  error.  The  reputation  of  a 
prince  may  be  a  peculiarly  unfair  measure  of  his  ability.  A  son 
whose  gifted  father  has  brought  the  nation's  affairs  into  a  pros- 
perous condition  may  thereby  get,  in  histories  and  biographies,  an 
unduly  high  rating;  whereas  a  son  who  must  strive  against  the 
unfavorable  conditions  produced  by  a  stupid  father,  may  thereby 
incur  an  undeserved  repute  of  inefficiency.  This  is,  however,  no 
more  plausible  a  supposition  than  the  opposite  one  that  a  moder- 
ately gifted  son  would  be  rated  too  low  by  contrast  with  a  gifted 
father  and  too  high  if  his  predecessor  had  been  a  marked  failure. 
On  the  whole  Dr.  Woods'  ratings  seem  little  subject  to  error 
other  than  chance  inaccuracy,  so  that  the  resemblances  calculated 
from  them  are  probably  too  low  rather  than  too  high. 

The  bulk  of  this  work  is  devoted  to  the  concrete  description 
of  particular  stocks  and  the  consequences  of  particular  matings. 
To  Dr.  Woods  at  least  the  likenesses  and  differences  of  these 
men  and  women  seem  due  in  very  large  measure  to  their  likeness 
and  difference  in  ancestry,  not  only  in  the  case  of  the  degree  of 
intellect  and  of  morals  but  also  in  the  direction  of  interests  and 
in  minor  features  of  temperament.  The  general  results  of  the 
measurements  of  resemblance  are  as  follows: — "By  taking  the 
records  of  each  country  separately  and  analyzing  them  minutely, 
we  have  seen  how  almost  perfectly  established  heredity  appears 
to  be  as  a  cause  of  decided  mental  and  moral  peculiarities, 
wherever  found.  Instead  of  treating  each  country  separately, 
the  entire  number  of  interrelated  persons  will  now  be  studied  as 
if  they  were  arranged  on  a  single  chart,  according  to  blood  rela- 
tionship. If  such  a  great  chart  were  constructed,  we  should  see 
the  geniuses,  or  (9)  and  (10)  grades,  not  scattered  at  random 
over  its  entire  surface,  but  isolated  little  groups  of  (9)  and  (10) 
characters  (the  individuals  within  each  group  contiguous  to  each 
other)   would  be  found  here  and  there.     One  such  group  would 


86  Educational  Psychology 

be  seen  centering  around  Frederick  the  Great,  another  around 
Queen  Isabella,  of  Spain,  another  in  the  neighborhood  of  William 
the  Silent,  and  still  a  fourth  with  Gustavus  Adolphus  as  a  center 
These  would  constitute  the  largest  groups  of  closely  related  (9) 
and  (10)  characters.  There  would  also  be  a  few  other  groups  of 
two  or  three  geniuses  each. 

"  Those  in  the  lowest  grades  for  intellect  would  also  be  found 
close  to  others  of  the  lowest  type,  and  would  fall  especially  in 
Spain  and  Russia,  in  which  countries  we  have  seen  an  inherited 
insanity.  There  would  be  certain  regions  composed  almost 
entirely  of  grades  from  (4)  to  (7).  These  would  cover  the 
greater  part  of  the  chart  and  include  the  houses  of  Hanover, 
Saxe-Coburg-Gotha,  Reuss,  Mecklenburg,  Hapsburg  in  Austria, 
Holstein,  Denmark,  Saxony,  Savoy,  Orleans  and  modern  Portu- 
gal."    ['06,  pp.  265-266.] 

The  general  tendency  to  resemblance  he  finds  to  be : — 
In  intellect : — 

Offspring  and  fathers,  r  =:  .30 ; 

Offspring  and  grandfathers,  r  =  .16; 

Offspring  and  great  grandfathers,  r   =   .15 
In  morals : — 

Offspring  and  fathers,  r  =  .30 

Offspring  and  grandfathers,  r  =  .175 
In  the  case  of  intellect  there  is  a  peculiarity  in  the  resemblance. 
Men  of  grades   i   to  4  have  equally  gifted  fathers ;  only   from 
then  on  is  there  a  rise  in  paternal  gifts  in  proportion  to  the  gifts 
of  the  offspring.     In  moral  qualities  it  is  not  so. 

Dr.  Woods  thinks  that  little  or  no  allowance  need  be  made  for 
greater  similarity  of  environment  for  son  and  father  or  grand- 
father than  existed  for  sons  of  royal  families  in  general.  He 
says  that,  while  educational  opportunities  have  been  unequal,  the 
"  advantages  and  hindrances  must  have  always  been  of  an  acci- 
dental character,  depending  on  various  causes,  and  their  distri- 
bution would  occur  largely  at  haphazard  throughout  the  entire 
number  of  collected  persons  (832)  ;  and  could  not  account  for 
the  great  group  of  mediocrity  and  inferiority,  like  the  houses  of 
Hanover,  Denmark,  Mecklenburg,  and  latter  Spain,  Portugal  and 
France."   ['06,  p.  284.] 

So  also  the  advantages  of  high  military  or  political  office  have 
been,  in  his  opinion,  distributed  "  at  random  throughout  the  entire 


The  Influence  of  Immediate  Ancestry  or  Family  87 

number  and  could  not  produce  the  grouping  by  close  blood  rela- 
tionship found  throughout  this  entire  study."   ['06,  p.  285.] 

He  tests  one  environmental  influence  by  the  facts,  namely,  the 
advantage  of  succession  to  the  throne.  "  There  is  one  peculiar 
way  in  which  a  little  more  than  half  of  all  the  males  have  had 
a  considerable  advantage  over  the  others  in  gaining  distinction  as 
important  historical  characters.  The  eldest  sons,  or  if  not  the 
eldest,  those  sons  to  whom  the  succession  has  devolved,  have 
undoubtedly  had  greater  opportunities  to  become  illustrious  than 
those  to  whom  the  succession  did  not  fall  by  right  of  primo- 
geniture. I  think  every  one  must  feel  that  perhaps  much  of  the 
greatness  of  Frederick  II,  of  Prussia,  Gustavus  Adolphus,  and 
William  the  Silent,  was  due  to  their  official  position ;  but  an  actual 
mathematical  count  is  entirely  opposed  to  this  view.  The  in- 
heritors of  the  succession  are  no  more  plentiful  in  the  higher 
grades  than  in  the  lower.  The  figures  below  show  the  number  in 
each  grade  who  came  into  power  by  inheriting  the  throne. 

Grades  i  23456789  10 

Total  number  in  each  Grade ..  .  7  21     41     49     71     70     68     43     18  7 

Succession  Inheritors 5  14     26     31     49     38     45     23       8  4 

Percent 71  67     63     64     69     54     67     54     67  57 

It  is  thus  seen  that  from  54  to  71  per  cent  inherited  the  suc- 
cession in  the  different  grades.  The  upper  grades  are  in  no  way 
composed  of  men  whose  opportunities  were  enhanced  by  virtue 
of  this  high  position.  Thus  we  see  that  a  certain  very  decided 
difference  in  outward  circumstances — namely,  the  right  of  suc- 
cession— can  be  proved  to  have  no  effect  on  intellectual  distinc- 
tion, or  at  least  so  small  as  to  be  immeasurable  without  much 
greater  data.  The  younger  sons  have  made  neither  a  poorer  nor 
a  better  showing."    ['06,  pp.  285-286.] 

His  conclusion  is  : — "  The  upshot  of  it  all  is,  that  as  regards 
intellectual  life,  environment  is  a  totally  inadequate  explanation. 
If  it  explains  certain  characters  in  certain  instances,  it  always 
fails  to  explain  as  many  more;  while  heredity  not  only  explains 
all  (or  at  least  90  per  cent)  of  the  intellectual  side  of  character 
in  practically  every  instance,  but  does  so  best  when  questions  of 
environment  are  left  out  of  the  discussion.  Therefore,  it  would 
seem  that  we  are  forced  to  the  conclusion  that  all  these  rough 
differences  in  intellectual  activity  which  are  susceptible  of  grad- 


88  Educational  Psychology 

ing  on  a  scale  of  ten  are  due  to  predetermined  differences  in  the 
primary  germ-cells."  ["06,  p.  286.] 

In  the  case  of  the  resemblances  in  morality  Dr.  Woods  is  less 
emphatic  in  denying  that  any  discount  for  similarity  in  training 
is  required.  In  fact  his  attitude  is  not  clear.  He  says,  "  The 
conclusion  seems  to  be,  therefore,  that  even  in  the  moral  side 
of  character,  inherited  tendencies  outweigh  the  effects  of  sur- 
roundings, for  the  reason  that,  applied  to  all  the  characters,  hered- 
ity is  able  to  explain  almost  every  one, — there  being  but  a  slight 
error  from  the  expected, — while  environment  will  only  explain 
a  relatively  smaller  number.  I  think  we  can  conclude  from  this 
that  in  each  individual,  inheritance  plays,  in  the  formation  of 
morality,  a  force  greater  than  50  per  cent.  Other  considerations 
enable  us  to  go  even  farther  than  this.  The  comparison  between 
maternal  and  paternal  grandsires  is  significant.  Offspring 
resemble  their  maternal  grandfathers  as  much  as  their  paternal. 
Here  we  test  the  resemblances  under  diverse  conditions  of  en- 
vironment, the  conditions  of  heredity  remaining  the  same,  yet 
we  find  no  weakening  of  the  latter  force.  Such  a  result  is  sur- 
prising, for  it  does  seem  improbable  that  environment  has  no 
influence  in  the  determination  of  temperament,  behavior,  and 
virtue  in  general ;  and  there  is,  of  course,  an  ingrained  popular 
behef  that  it  has."    ['06,  p.  294.] 

But  only  a  page  later  he  adds,  "  All  I  can  say  is,  that  I  have 
made  several  tests  to  find  a  measurable  influence  of  environment 
apart  from  inheritance,  and  have  failed  to  find  it  in  this  research." 
['06,  p.  295.]  In  discussing  the  fact  that  the  same  stock  shows 
both  very  bad  and  very  good  men  and  women,  he  says,  "It  is 
these  strong  contrasts,  more  than  anything  else,  that  must  lead  us 
to  the  conclusion  that  what  we  have  in  Plate  2  [a  chart  showing 
moral  resemblance  of  offspring  and  parents,  not  reprinted  here] 
is  truly  the  effect  of  blood  relationship,  for  environment  should 
not  cause  this  distribution.  Spain,  France,  and  Russia  give  us 
most  of  the  degenerates.  In  these  countries  the  individuals  are 
closely  associated  in  blood  with  insanity,  epilepsy,  or  other  psy- 
choses.   This  is  itself  a  coincidence  to  be  explained  by  those  who 

doubt  that  morality  is  much  the  result  of  inheritance 

When  strong  contrasts  are  found  among  the  children,  we  always 
find  strong  contrasts  among  the  ancestors."     ['06,  pp.  290-292.] 

In    1905   the   author  published   a   report    [Thorndike,    '05]    of 


The  Influence  of  hnmediate  Ancestry  or  Family  89 

measurements  of  the  resemblances  of  fifty  pairs  ot  twins  in 
marking  A's  on  a  printed  page  of  capital  letters  (A  test),  mark- 
ing words  containing  certain  combinations  of  letters  (a-t  and  r-e), 
marking  misspelled  words  on  a  sheet  containing  100  words  (mis- 
spelled word  test),  addition,  multiplication  and  writing  the  oppo- 
sites  of  a  set  of  words.*  I  quote  or  summarize  the  essential  facts. 
The  resemblances  of  twins,  resemblance  meaning  any  greater 
likeness  than  would  be  found  in  a  pair  of  children  of  the  same 
age  and  sex  picked  at  random  from  the  school  population  of  Xew 
York  City,  are: — 

In  the  A  test  R  =  .69 

In  the  a-t  and  r-e  tests  R  =  .7i 

In  the  misspelled  word  test       R  =  .80  4- 

In  addition  R  =  .75 

In  multiplication  R  =  .84 

In  the  opposites   test  R  =  .90 

There  were  two  possible  sources  of  error  in  the  measurements : — 
namely,  (i)  the  possibly  unfair  selection  of  twins  and  (2)  the 
fact  that  the  two  members  of  a  pair  were  commonly  tested  to- 
gether. The  method  of  discovering  twins  was  as  follows : — 
Teachers  in  certain  schools  were  asked  to  inquire  of  their  pupils 
whether  any  one  had  a  twin  brother  or  sister.  All  twins  so 
reported  were  tested.  But  also  frequently  some  teachers  would 
report  that  in  such  and  such  a  school  there  was  a  pair  of  twins. 
These  could  then  be  found  quickly  and  measured.  These  reported 
cases  were  perhaps  likely  to  have  been  noticed  in  the  first  case 
because  of  their  likeness  and  so  to  be  an  unfair  selection.  Again, 
in  the  New  York  schools  it  is  usual  to  separate  the  sexes  after 
three  or  four  years  of  school  life,  and  it  is  a  frequent  practice 
to  separate  them  from  the  start.  Twins  of  like  sex  are  therefore 
more  conveniently  obtained  and  so  more  often  tested  than  their 
general  frequency  would  recommend.  The  amount  of  the  result- 
ing constant  error  is  not.  however,  great. f  The  tests  were  all 
made  by  the  same  individual  and  in  the  same  way  except  for 

*These   tests   are   more   exactly   describej   in   Appendix  II. 

fOf  the  fifty  pairs  of  twins  measured  there  were  three  more  of  the  same 
sex  than  would  be  expected  in  a  random  selection. 


90  Educational  Psychology 

unconscious  changes.  However,  in  respect  to  time  of  day,  con- 
ditions of  weather  and  light,  and  such  conditions  as  are  deter- 
mined by  family  life,  e.  g.,  the  lack  of  breakfast,  fatigue  from  a 
party  the  previous  night,  and  the  like,  two  twins  would,  when 
measured  at  the  same  time,  be  influenced  alike.  Thus  the  obtained 
resemblance  would  be  too  large.  I  can  evaluate  the  amount  of  the 
resultant  constant  error  only  from  general  considerations.  I  be- 
lieve it  to  be  small.  This  constant  error  would  also  influence 
the  correction  made  from  attenuation,  but  here  would  make  the 
obtained  resemblance  too  small.  An  allowance  was  made  for 
these  two  sources  of  error  to  the  best  of  the  author's  ability. 

If  now  these  resemblances  are  due  to  the  fact  that  the  two  mem- 
bers of  any  twin  pair  are  treated  alike  at  home,  have  the  same 
parental  models,  attend  the  same  school  and  are  subject  in  general 
to  closely  similar  environmental  conditions,  then  (i)  twins  should, 
up  to  the  age  of  leaving  home,  grow  more  and  more  alike,  and  in 
our  measurements  the  twins  13  and  14  years  old  should  be  much 
more  alike  than  those  9  and  10  years  old.  Again,  (2)  if  similarity 
in  training  is  the  cause  of  similarity  in  mental  traits,  ordinary 
fraternal  pairs  not  over  four  or  five  years  apart  in  age  should  show 
a  resemblance  somewhat  nearly  as  great  as  twin  pairs,  for  the  home 
and  school  conditions  of  a  pair  of  the  former  will  not  be  much  less 
similar  than  those  of  a  pair  of  the  latter.  Again,  (3)  if  training 
is  the  cause,  twins  should  show  greater  resemblance  in  the  case  of 
traits  much  subject  to  training,  such  as  ability  in  addition  or  in 
multiplication,  than  in  traits  less  subject  to  training,  such  as  quick- 
ness in  marking  ofif  the  A's  on  a  sheet  of  printed  capitals,  or  in 
writing  the  opposites  of  words. 

On  the  other  hand,  (i)  the  nearer  the  resemblance  of  young 
twins  comes  to  equaling  that  of  old,  (2)  the  greater  the  superiority 
of  twin  resemblance  to  ordinary  fraternal  resemblance  is,  and  (3) 
the  nearer  twin  resemblance  in  relatively  untrained  capacities 
comes  to  equaling  that  in  capacities  at  which  the  home  and  school 
direct  their  attention,  the  more  must  the  resemblances  found  be 
attributed  to  inborn  traits. 

The  older  twins  show  no  closer  resemblance  than  the  younger 
twins,  and  the  chances  are  surely  four  to  one  that  with  an  infinite 
number  of  twins  tested  the  12-14-year-olds  would  not  show  a 
resemblance  .15  greater  than  the  9-11-year-olds.    The  facts  are: — 


The  Influence  of  Immediate  Ancestry  or  Family  91 

The  resemblances  of  young  and  old   twins  compared 


Twins 

9-1 1 

Twins 

12-14 

i)  A  test 

66 

7i 

2)  a-t  and  r-e  tests 

81 

62 

3)   Misspelled  word  test 

76 

74 

4)   Addition 

90 

54 

5)   Multiplication 

91 

69 

6)   Opposites 

96 

88 

Averages 

83 

70 

I  have  measured  the  resemblances  between  siblings  (children 
of  the  same  parents)  a  few  years  apart  in  age  only  imperfectly, 
and  only  in  the  A  test,  a-t  test  and  opposites  tests.  The  resem- 
blances are  between  .3  and  .4,  or  less  than  half  the  resemblance 
found  for  twins. 

The  variations  in  the  closeness  of  resemblance  of  the  twins  in 
the  different  traits  show  little,  and  possibly  no,  direct  correlation 
with  the  amount  of  opportunity  for  environmental  influences.  The 
traits  most  subject  to  training  (addition  and  multiplication)  do 
show  closer  resemblances  than  the  traits  least  subject  to  training 
(the  A,  a-t  and  r-e  test)  ;  but  on  the  other  hand  show  less  close 
resemblances  than  the  traits  moderately  subject  to  training  (the 
misspelled  word  test  and  opposites  test).     (See  page  89.) 

The  facts  then  are  easily,  simply  and  completely  explained  by 
one  simple  hypothesis :  namely,  that  the  natures  of  the  germ 
cells — the  conditions  of  conception — cause  whatever  similarities 
and  differences  exist  in  the  original  natures  of  men,  that  these 
conditions  influence  body  and  mind  equally,  and  that  in  life  the 
differences  in  modification  of  body  and  mind  produced  by  such 
differences  as  obtain  between  the  environments  of  present-day 
New  York  City  public  school  children  are  slight. 

We  must  be  careful,  however,  not  to  confuse  two  totally  dif- 
ferent things  :  ( i )  the  power  of  the  environment, — for  instance, 
of  schools,  laws,  books  and  social  ideals, — to  produce  differences 
in  the  relative  achievements  of  men,  and  (2)  the  power  of  the 
environment  to  produce  differences  in  absolute  achievement.  It 
has  been  shown  that  the  relative  differences  in  certain  mental 
traits  which  were  found  in  these  one  hundred  children  are  due 
almost  entirely  to  dift'erences  in  ancestry,  not  in  training ;  but  this 
does  not  in  the  least  deny  that  better  methods  of  training  might 
improve  all  their  achievements  fifty  per  cent  or  that  the  absence 


92  Educational  Psychology 

of  training,  say,  in  spelling  and  arithmetic,  might  decrease  the 
corresponding  achievements  to  zero. 

The  argument  is  limited  entirely  to  the  causes  which  make  one 
person  differ  from  another  in  mental  achievements  under  the  same 
general  conditions  of  life  at  the  beginning  of  the  twentieth  century 
in  New  York  City  as  pupils  in  its  school  system.  If  the 
resemblance  of  twins  had  been  measured  in  the  case  of  a  group 
made  up  partly  of  New  York  City  school  children  and  partly  of 
children  of  equal  capacity  brought  up  in  the  wilds  of  Africa,  the 
variability  of  the  group  in  addition  and  multiplication  would  have 
increased  and  the  correlation  coefficients  would  rise.  They  would 
then  measure  the  influence  of  original  nature  plus  the  now  much 
increased  influence  of  the  environment. 

Heymans  and  Wiersma  ["06  and  '07]  sought  to  measure  the 
influence  of  heredity  by  having  the  parents  and  children  in  a 
family  rated  by  some  one  who  knew  them  well.  Such  reports 
were  obtained  from  physicians  through  a  questionnaire.  The 
ratings  were  under  ninety  rubrics  of  which  the  following  are 
samples : — 

1.  Is  the  person  in  question  active  (gesticulating,  jumping  up 
from  the  chair,  going  up  and  down  the  room)  or  passive  and 
quiet  ? 

2.  Is  the  person  in  question,  in  his  professional,  business,  school 
or  home  life,  always  zealous  at  his  work,  or  only  sometimes 
zealous,  or  outright  lazy? 

The  resulting  ratings  suffer  from  the  constant  error  toward  too 
great  resemblance  due  to  the  fact  that  any  one  family  is  judged 
with  reference  to  the  same  dividing  line  for  a  trait,  the  line 
being  in  a  different  place  along  the  scale  for  each  judge.  This 
source  of  error  is  even  more  mischievous  here  than  in  Pearson's 
study,  since  here  apparently  one  judge  commonly  rated  only  one 
family.  They  also  suffer  from  the  random  inaccuracy  of  the 
judgments  which,  as  was  shown  on  page  80,  would  make  the 
obtained  resemblances  too  low. 

The  authors  do  not  measure  the  resemblances  in  the  usual  way 
nor  give  data  permitting  anyone  else  to  do  so.  In  view  of  the 
insecurity  of  their  original  data  it  seems  best  not  to  enter  upon 
an  explanation  of  their  somewhat  awkward  method  of  measuring 
the  force  of  heredity,  and  not  to  repeat  the  figures  which  are  got  by 
this  method.     The  authors  do  not  attempt  to  estimate  an  allow- 


The  Influence  of  Immediate  Ancestry  or  Family  93 

ance  for  the  influence  of  similarity  in  home  training,  though  they 
state  that  some  such  allowance  must  be  made. 

They  point  out,  however,  that  there  is  reason  to  believe  that 
the  influence  of  heredity  far  outweighs  the  influence  of  home 
training,  since  the  resemblance  is  hardly  any  greater  in  traits 
much  subject  to  the  latter  influence  than  in  traits  little  subject  to  it. 
They  instance  industry,  sympathy  and  patriotism  on  the  one  hand 
and  emotionality,  consolability,  and  memory  on  the  other. 

The  Specialization  of  the  Influence  of  Near  Ancestry 

In  the  facts  so  far  given  in  this  chapter,  the  emphasis  has  been 
upon  the  amount  of  influence  of  near  ancestry.  The  degree  to 
which  it  is  specialized  is  also  of  importance.  How  far,  for 
example,  do  particular  talents  exist  in  a  man's  original  nature  as 
a  result  of  his  ancestry?  Is  a  man  from  the  beginning  organized 
to  be  a  novelist,  or  only  to  be  a  writer  of  fiction,  or  only  to  be  an 
artist  of  some  sort,  or  perhaps  even  only  to  be  a  man  of  ability? 
How  far  is  this  original  specialization,  if  it  exists,  due  to 
ancestry?  It  is  a  plausible  statement  that  individual  minds  are 
dependent  on  heredity  only  in  their  rough  outlines,  the  currents 
of  mental  activity  being  fixed  only  in  their  general  directions  and 
left  to  take  what  particular  channels  circumstances  may  decide. 
But  this  or  any  other  opposite  statement  must  be  put  in  terms 
of  '  how  much  ',  '  how  far  ",  '  in  what  cases  ',  to  be  theoretically 
satisfying  or  practically  useful. 

Galton,  who  had  this  problem  clearly  in  mind,  notes  a  number 
of  relevant  facts,  some  of  which  I  quote.  Concerning  the  judges 
of  England  between  1660  and  1865  he  says:  "Do  the  judges 
often  have  sons  who  succeed  in  the  same  career,  where  success 
would  have  been  impossible  if  they  had  not  been  gifted  with  the 
special  qualities  of  their  fathers  ?  .  .  . 

"  Out  of  the  286  judges,  more  than  one  in  every  nine  of  them 
have  been  either  father,  son  or  brother  to  another  judge,  and 
the  other  high  legal  relationships  have  been  even  more  numerous. 
There  cannot,  then,  remain  a  doubt  but  that  the  peculiar  type 
of  ability  that  is  necessary  to  a  judge  is  often  transmitted  by 
descent."     ['69,  '92,  pp.  61  and  62.] 

Concerning  the  eminent  relatives  of  eminent  statesmen  he 
says :  "  Thirdly,  the  statesman's  type  of  ability  is  largely  trans- 
mitted or  inherited.     It  would  be  tedious  to  count  the  instances 


94  Educational  Psychology 

in  favour.  Those  to  the  contrary  are  Disraeli,  Sir  P.  Francis  (who 
was  hardly  a  statesman,  but  rather  a  bitter  controversialist)  and 
Horner.  In  all  the  other  35  or  36  cases  in  my  appendix,  one  or 
more  statesmen  will  be  found  among  their  eminent  relations.  In 
other  words,  the  combination  of  high  intellectual  gifts,  tact  in 
dealing  with  men,  power  of  expression  in  debate,  and  ability  to 
endure  exceedingly  hard  work,  is  hereditary."  ['69,  '92,  pp.  103 
and  104.] 

Similar  specialization  of  inheritance  is  shown  to  be  the  case 
with  the  relatives  of  great  commanders,  literary  men,  poets  and 
divines.  With  men  of  science  the  fact  is  much  more  pronounced, 
twenty-two  out  of  the  twenty-six  eminent  sons  of  eminent  scientific 
men  having  been  eminent  in  science.  This  extreme  specialization 
of    resemblance    is    in    part    due,    Galton    thinks,    to    training. 

The  eminent  relatives  of  eminent  painters  seem  to  be  well- 
nigh  universally  gifted  in  the  same  special  line.  In  Galton's  list 
all  the  relatives  mentioned  are  painters  save  four.  These  were 
gifted  in  sculpture  (2),  music  (i)  and  embroidery  (i).  Finally, 
"  Mendelssohn  and  Meyerbeer  are  the  only  musicians  in  my  list 
whose  eminent  kinsmen  have  achieved  their  success  in  other 
careers  than  that  of  music."    ['69,  '92,  p.  231.] 

Of  course  there  is,  in  the  case  of  all  of  Galton's  facts,  the 
possibility  that  home  surroundings  decided  the  special  direction 
which  genius  took,  that  really  original  nature  is  organized  only 
along  broad  lines.  Moreover,  it  is  difficult  to  see  just  what  in  the 
nervous  system  could  correspond  to  a  specialized  original  capacity, 
say,  to  be  a  judge.  Still  the  latter  matter  is  a  question  of  fact, 
and  of  the  former  issue  Galton's  studies  make  him  the  best  judge. 
We  should  not?  also  that  it  is  precisely  in  the  traits  the  least 
amenable  to  environmental  influence,  such  as  musical  ability,  that 
the  specialization  of  family  resemblance  is  most  marked. 

Ellis  notes  '  a  clearly  visible  tendency  for  certain  kinds  of  ability 
to  fall  into  certain  [family]  groups.'  ['04,  p.  83.]  In  his  group 
of  1030  eminent  men  he  finds  that,  "  Men  of  letters  are  yielded 
by  every  class,  perhaps  especially  by  the  clergy,  but  Shakespeare, 
and  it  is  probable  Milton,  belonged  to  the  families  of  yeomen.  The 
sons  of  lawyers,  one  notes,  even  to  a  greater  extent  than  the 
eminent  men  of  "  upper  class  "  birth,  eventually  find  themselves 
in  the  House  of  Lords,  and  not  always  as  lawyers.  The  two 
groups  of  Army  and  Medicine  are  numerically  close  together,  but 


The  Influence  of  Immediate  Ancestry  or  Family  95 

in  other  respects  very  unlike.  The  sons  of  army  men  form  a  very 
brilliant  and  versatile  group,  and  include  a  large  proportion  of 
great  soldiers ;  the  sons  of  doctors  do  not  show  a  single  eminent 
doctor,  and  if  it  were  not  for  the  presence  of  two  men  of  the 
very  first  rank — Darwin  and  Landor — they  would  constitute  a 
comparatively  mediocre  group. 

"Painters  and  sculptors  constitute  a  group  which  appears  to  be 
of  very  distinct  interest  from  the  point  of  view  of  occupational 
heredity.  In  social  origin,  it  may  be  noted,  the  group  differs 
strikingly  in  constitution  from  the  general  body,  in  which  the 
upper  class  is  almost  or  quite  predominant.  Of  63  painters  and 
sculptors  of  definitely  known  origin,  only  two  can  be  placed  in 
the  aristocratic  division.  Of  the  remainder  7  are  the  sons  of 
artists,  22  the  sons  of  craftsmen,  leaving  only  32  for  all  other 
occupations,  which  are  mainly  of  lower  middle  class  character, 
and  in  many  cases  trades  that  are  very  closely  allied  to  crafts. 
Even,  however,  when  we  omit  the  trades  as  well  as  the  cases  in 
which  the  fathers  were  artists,  we  find  a  very  notable  predominance 
of  craftsmen  in  the  parentage  of  painters,  to  such  an  extent  indeed 
that  while  craftsmen  only  constitute  9.2  per  cent  among  the 
fathers  of  our  eminent  persons  generally,  they  constitute  nearly 
35  per  cent  among  the  fathers  of  the  painters  and  sculptors.  It  is 
difficult  to  avoid  the  conclusion  that  there  is  a  real  connection 
between  the  father's  aptitude  for  craftsmanship  and  the  son's 
aptitude  for  art. 

"To  suppose  that  environment  adequately  accounts  for  this 
relationship  is  an  inadmissible  theory.  The  association  between 
the  craft  of  builder,  carpenter,  tanner,  jeweller,  watchmaker,  wood- 
carver,  rope  maker,  etc.,  and  the  painter's  art  is  small  at  the  best, 
and  in  most  cases  non-existent."     ['04,  pp.  84,  85.] 

Ellis  adds,  "  It  may  be  noted  that  Arreat  {Psychologic  dii 
Peintre,  1892,  ch.  11)  in  investigating  the  heredity  of  200  eminent 
European  painters,  reached  results  that  are  closely  similar  to 
those  I  have  reached  in  my  smaller  purely  British  group.  He 
found  that  very  few  were  of  upper  class  social  rank,  and  those 
not  usually  among  the  most  important,  while  nearly  two-thirds  of 
the  whole  number  were  found  to  be  the  sons  either  of  painters 
or  of  workers  in  some  art  or  craft.  He  refers  to  the  special 
frequency  of  jewellers  among  the  fathers.  I  may  remark  that  in 
my  list,  working  jewellers  and  watchmakers  occurred  twice,  a 


96  Educational  Psychology 

small  number,  but  relatively  large  considering  that  there  are  only 
three  fathers  of  this  occupation  in  the  total  parentage  -of  British 
men  of  ability."     ["04,  p.  85.] 

Pearson's  measurements  concern  somewhat  specialized  traits 
from  the  start.  In  so  far  as  his  results  are  trustworthy  they 
show  equal  resemblance  in  so  specialized  a  trait  as  temper  or  hand- 
writing with  that  found  for  '  ability.'  Woods  notes  the  inheritance 
of  literary  ability,  of  common  sense,  of  insanity  and  other  some- 
what specialized  traits  in  the  royal  families.  In  the  twins  whom 
I  measured  the  resemblance  is  almost  or  quite  as  great  in  the  case 
of  any  one  of  the  six  tests  (see  p.  89)  as  in  the  average  ability 
in  all  of  them. 

From  the  work  of  Burris  [03],  if  his  results  are  properly 
corrected  for  the  chance  inaccuracies  in  the  original  measures,  it 
would  appear  that  the  ability  to  do  well  in  some  one  high  school 
study  is  nearly  or  quite  as  much  due  to  ancestry  as  is  the  ability 
to  do  well  in  the  course  as  a  whole. 

What  knowledge  we  have  thus  supports  the  view  that  a  man's 
original  nature  is  organized  by  inheritance  in  great  detail, 
particular  traits  and  complexes  of  traits  showing  similarity  be- 
tween father  and  son  or  brother  and  brother. 

Mental  inheritance  is  specialized  also  in  the  further  sense  that 
two  individuals  alike  in  one  trait  as  a  result  of  heredity  need  not 
be  equally  alike  in  some  other  trait,  though  the  latter  be  in  general 
equally  subject  to  inheritance.  For  example,  a  pair  of  twins 
may  be  indistinguishable  in  eye  color  and  stature  but  notably 
different  in  hair  color  and  in  tests  of  intellect. 

To  measure  the  extent  of  this  specialization  of  resemblance, 
exact  measures  of  the  resemblance  of  individual  relatives  are 
needed.  The  procedure  required  to  measure  accurately  the 
resemblance  between  one  individual  and  another  in  one  trait  is 
somewhat  intricate,  and  I  shall  not  describe  it  here.  The  reader 
may  verify  the  accuracy  of  the  measures  which  I  give  by  examin- 
ing Measurements  of  Twins,  [Thorndike,  '05]  sections  16  to  18 
and  21  to  23.  Here  I  shall  simply  give  the  resemblances  in 
efficiency  in  the  A  test,  a-t  test,  and  misspelled  word  test  of  the 
ten  pairs  of  twins  who  showed  the  closest  resemblance  in  efficiency 
in  addition,  multiplication,  and  writing  opposites.  These  show 
(Table  9)  that  very  close  resemblance  in  efficiency  in  'association  ' 
may  go  with  actual  antagonism,  or  greater  unlikeness  than  that 


The  Influence  of  Immediate  Ancestry  or  Family 


97 


shown  by  children  of  the  same  age,  taken  at  random,  in  efficiency 
in  tests  of  '  perception.' 

TABLE  9. 
Specialization  of  Resemblance  in  Twins. 
Resemblance  in  association :    Resemblance  in  perception : 


Twin  pair 


resemblance  in  efficiency 

in  add.,  mult,  and  oppos. 

combined. 


2 

102 

1 .00 — 

17 

"7 

•99 

20 

120 

1 .00 — 

21 

121 

•99 

26 

126 

•95 

27 

127 

.94— 

33 

133 

•95 

36 

136 

•94 

46 

146 

1 .00 — 

48 

148 

1 .00 — 

resemblance  in  A  test, 

word  test  and  misspelled 

word  test  combined. 

28 

83 
88 
86 

GO 

GO 

OG 

73 


97 

In  the  Measurements  of  Twins  I  have  also  shown  in  detail  that 
twins  may  be  indistinguishable  in  any  one  physical  trait  without 
being  at  all  similar  in  certain  others,  or  in  certain  mental  traits. 
For  example,  a  pair  of  twins  may  show  resemblance  of  .95  to  i.oo 
in  bodily  measurements  other  than  head  measurements  and  of  o  in 
head  measurements. 

As  a  consequence  of  the  specialization  of  resemblance  the  fact 
of  '  a  child  resembling  his  parents '  is  seen  to  be  in  reality  'the 
mental  traits  of  a  child  resembling  each  the  corresponding  mental 
trait  in  his  parents.'  Each  trait  or  '  character  '  may  be  inherited 
in  more  or  less  independence  of  other  traits  or  '  characters.' 

The  Analysis  of  Mental  Inheritance 

It  has  been  noted  that  the  fundamental  fact  in  mental  inheritance 
is  the  relation  between  the  germ  making  the  parent  and  the  germ 
making  the  child,  not  between  the  parent  and  child  themselves. 
It  has  also  been  noted  that  inheritance  is  not  merely  of  total 
natures  vaguely,  but  of  particular  details,  traits  of  '  character ' 
each  more  or  less  independently  of  the  rest.  So  far  as  mental 
traits  are  thus  inherited,  we  have  to  think  of  each  amount  of  each 
trait  as  possessing  some  determiner  in  the  germs  and  of  the  deter- 
miners of  any  one  trait  in  different  generations  of  germs  as 
standing  in  some  relation. 


98  Educational  Psychology 

What  is  called  Mendelism  or  Mendelian  inheritance  (after  its 
discoverer,  Gregor  Mendel)  offers  an  account  of  certain  features 
of  these  determiners  and  of  the  relations  in  which  determiners 
of  the  same  trait  in  successive  generations  of  a  family  stand. 

In  its  clearest  and  most  unlimited  form*  this  account  would 
state  that : — 

First. — The  determiner  perpetuates  itself  with  little  or  no  vari- 
ation. No  such  differences  exist  between  the  determiners  of 
trait  A  in  germ  generation  i  and  the  determiners  of  trait  A  in 
germ  generation  2,  as  are  found  between  parents  and  children. 

Second. — One  fertilized  ovum  has  either  (i)  no  determiner  for 
trait  A  (when  neither  germ  nor  ovum  had  one),  or  (2)  a  single 
determiner  (when  either  the  germ  alone  or  the  ovum  alone  had 
one)  or  a  double  determiner  (when  both  germ  and  ovum  had  one). 

Third. — The  germ  cells  later  developing  from  one  fertilized 
ovum  will  in  these  three  cases  respectively  be  (i)  all  without  the 
determiner,  or  (2)  half  with  it  and  half  without  it,  or  (3)  all 
with  it. 

Fourth. — Any  difference  between  one  man  and  another  in 
original  nature  is  reducible  to  the  presence  or  absence  of  such 
determiners.  Variation  in  them  or  blends  of  one  with  another  are 
not  required. 

Fifth. — A  '  character '  or  trait  or  feature  of  an  individual  may 
be  a  unit  character  or  a  multiple  character.  A  unit  character  is 
one  which  is  caused  by  the  presence  of  one  single  or  double  deter- 
miner in  the  fertilized  ovum  from  which  the  individual  developed 
(positive  unit  character),  or  by  the  absence  of  one  single  or 
double  determiner  (negative  unit  character).  A  multiple  character 
is  one  caused  (i)  by  the  presence  of  determiners  of  more  than 
one  sort,  or  (2)  by  the  absence  of  determiners  of  more  than  one 
sort,  or  (3)  by  the  presence  of  one  or  more  and  the  absence  of 
one  or  more  of  a  different  sort. 

These  laws  may  be  illustrated  as  follows :  Call  the  condition 
of  a  character,  say  A,  in  the  individual  which  is  produced  by  a 
single  determiner  in  the  fertilized  ovum  from  which  he  springs, 
A  simplex.     Call  the  condition  of  the  corresponding  character  in 

*There  are  other  possible  views  of  the  implications  of  the  Mendelian 
results  with  respect  to  the  nature  of  the  determiners,  their  behavior  and 
their  relations  to  the  '  characters  '  that  result  from  them.  There  are  also 
other  views  of  the  universality  of  the  laws  given  here. 


The  Influence  of  Immediate  Ancestry  or  Family  99 


the  individual  which  is  produced  by  a  double  determiner  in  the 
fertilized  ovum,  A  duplex. 

Suppose  cooperativeness  to  be  a  positive  unit  character.  Call 
it  C,  and  call  its  determiner  c.  Then  the  condition  in  the  parents 
may  be: — (i)  both  with  C  duplex,  (2)  one  with  C  duplex  and  one 
with  C  simplex,  (3)  both  with  C  simplex,  (4)  one  with  C  duplex 
and  one  without  C,  (5)  one  with  C  simplex  and  one  without  C, 
(6)  both  without  C.    The  results  will  be  as  follows : 


(i)  If  all  ova  have  c  and  all 

sperms  have  e 

(2)  If  all  ova  have  c  and  half 

of  the  sperms  have  c, 

or 

if  half  of  the  ova  have  c 

and  all  sperms  have  c 


(3)  If  half  of  the  ova  have  c 
and  half  of  the  sperms 
have  c 


(4)  If  all  ova  have  c  and  no 

sperms  have  c 
or 
if  all  sperms  have  c  and 
no  ova  have  c 

(5)  If  half  of  the  ova  have  c 

and  no  sperms  have  c 
or 
if  none  of  the  ova  have  c 
and  half  of  the  sperms 
have  c 

(6)  If  no  ova  have  c  and  no 

sperms  have  c 


the  unions  will  have  \  J"  and   the    offspring 

2c  /  I  will  have  C  duplex. 

half    of    the    unions  1  /  and    the    offspring 

will  have  2c  J  \  will  have  C  duplex. 

half    of    the    unions  \  /  and   the    offspring 

will  have  I  c  /  \  will  have  C  simplex. 

one-fourth  of  the  un-  1  f  and   the    offspring 

ions  will  have  2c  j  \  will  have  C  duplex. 

one-half   of   the   un-  1  /  and   the    offspring 

ions  will  have   ic  J  \  will  have  C  simplex. 

one-fourth  of  the  un-  "I  /  and   the    offspring 

ions  will  have  no  c  J  \  will  have  no  C. 


the  unions  will  have  \  /  and    the    offspring 
IC  /   \  will  have  C  simplex. 


half    of    the    unions 
will  have  ic 

half    of    the    unions 
will  have  no  c 

none   of   the   unions 
will  have  c 


and   the    offspring 
will  have  C  simplex . 

f  and    the    offspring 
\  will  have  no  C. 

/  and  none  of  the  off- 
\  spring  will  have  C. 


These  results  seem  at  first  sight  in  sharp  contrast  with  the  so 

common  fact  of  blended  inheritance.    Blended  inheritance  denotes 

the  appearance,  in  offspring  from  parents  possessing  A.  and  B 

A  -f-  B 
respectively,  of  conditions  tending  toward ,  these  conditions 

varying  amongst  the  offspring  around  one  central  tendency  and 
not  falling  at  all  into  two  or  three  distinct  groups.  But  the  gross 
facts  of  blended  inheritance  in  a  trait  could  perfectly  well  come 
by  the  action  of  the  strict  Mendelian  laws  if  the  trait  depended 
on  a  sufficiently  large  number  of  different  determiners. 

It  is  interesting  to  see  the  resulting  gradations  if  two,  three, 
four,  and  more  determiners  produce  each  an  amount  of  the  same 


lOO 


Educational  Psychology 


mental  trait.  Suppose,  for  example,  that  a,  b,  and  c  are  deter- 
miners of  intellect,  aa,  bb,  and  cc  being  the  normal  double 
determiners.  Suppose  aa  to  produce  in  the  individual  an  amount 
of  intellect  represented  by  2q,  bb  to  produce  an  amount  represented 
by  4q,  and  cc  to  produce  an  amount  represented  by  8q.  Suppose 
a,  b,  and  c  to  produce  each  approximately  half  as  much  as  aa, 
bb,  and  cc,  respectively. 

The  union  of  a  germ  and  ovum  could  have : — 

o     giving  o  degrees  of  intellect  in  the  individual, 


or  a 

iq 

"  b 

2q 

"  Q    " 

4q 

"  aa 

2q 

"  ab   " 

3q 

"  ac 

5q 

"  bb   ' 

4q 

"  be   ' 

6q 

"  cc   ' 

8q 

"  aab  ' 

4q 

"  aac  ' 

6q 

"  aab  ' 

sq 

or  any  one  of  many  other  combinations  of  the  determiners,  such 
as  aabbcc,  aabbc,  abbe,  etc.  The  resulting  degrees  of  intellect 
would  vary  from  o  to  I4q  by  steps  of  one. 

The  offspring  of  two  individuals  would  then  commonly  show 
with  respect  to  intellect  as  a  whole  a  great  variety  of  degrees 
as  in  blended  inheritance,  though  the  result  with  respect  to  the 
effect  of  any  one  determiner  followed  pure  Mendelian  principles. 
For  example,  suppose  one  individual  to  possess  the  character  due 
to  a,  duplex ;  that  due  to  c,  simplex ;  and  to  lack  that  due  to  b. 
His  intellect  will  be  6.  Suppose  another  to  possess  the  character 
due  to  a,  simplex ;  that  due  to  c,  duplex ;  and  that  due  to  b, 
simplex.  His  intellect  will  be  ii.  On  Mendelian  principles  the 
germs  of  the  first  individual  will  comprise  germs  with  a  and  c 
and  germs  with  a  alone.  The  germs  of  the  second  individual 
will  comprise  germs  with  a,  c,  and  b,  germs  with  a  and  c,  and 
germs  with  b  and  c.  The  unions  will  comprise  ac  +  acb,  ac  +  ac, 
ac  +  bc,  a  +  acb,  a  +  ac,  and  a  +  bc.  The  resulting  intellects  will 
comprise  degrees  12,  10,  11,  8,  6,  and  7.  Mendelian  principles  applied 


The  Influence  of  Immediate  Ancestry  or  Family        loi 

to  the  elementary  factors  of  heredity  might  then  give,  with  respect 
to  the  total  traits  compounded  of  these  factors,  a  continuous 
gradation  and  all  the  complexities  of  mental  inheritance  that 
observation  finds. 

Many  features  of  animals  and  plants  have  been  more  or  less 
perfectly  analyzed  into  their  unit  characters,  and  the  determiners 
of  these  have  been  got  under  control  in  breeding,  so  that  strains 
with  a  desirable  determiner  present  in  all  the  germs  have  been 
established.  Undesired  determiners  have  been  weeded  out  of  all 
the  germs  of  certain  individuals,  so  that  the  offspring  from  any 
two  of  these  individuals  are  sure  to  be  free  of  the  undesired 
character. 

The  Mendelian  ideal  is  to  represent  all  of  each  man's  original 
nature  by  a  list  of  unit  characters,  to  refer  each  of  these  to  its 
determiner,  and  to  determine  the  future  of  the  race  by  arranging 
selection  and  elimination  of  the  determiners.  This  ideal  is,  in 
almost  all  ways,  a  great  advance  over  the  older  plan  of  represent- 
ing each  man  by  a  list  of  qualities  chosen  largely  by  historical 
accidents,  referring  these  vaguely  to  the  germ  plasm,  and  seeking 
to  determine  the  race's  future  by  selection  and  elimination  of 
individuals. 

In  one  respect,  however,  it  may  not  be  better.  This  concerns 
its  insistence  on  the  invariability  of  the  determiners  from  genera- 
tion to  generation,  and  within  each  fraternity  of  germs.  If  this 
invariability  is  perfect,  any  unit  character  can  appear  in  only 
two  forms  or  degrees,  one  corresponding  to  the  presence  of  a 
double  determiner  in  the  united  sperm  and  ovum  whence  the 
individual  developed,  and  one  corresponding  to  the  presence  of  a 
single  determiner.  But  if  this  requirement  is  made  strictly,  it  is 
hard  to  find  any  unit  characters.  Curliness  of  hair  and  brownness 
of  eye,  for  instance,  seem  to  be  far  from  constant.  The  former 
may  be  separated  fairly  clearly  from  straightness,*  but  within  its 
own  range  it  varies  from  waviness  to  extreme  kinkiness. 

As  a  result  of  the  difficulty  of  finding  any  traits  appearing  in 
only  two  degrees  each  substantially  invariable,  many  students  of 
heredity  would  frankly  admit  that  the  determiners  did  vary  some- 
what and  that  one  determiner  could  blend  with  another  similar 
determiner. 

•Though  even  this  may  be  doubted. 


102  Educational  Psychology 

Mendelian  Inheritance  in  the  Case  of  Intellectual  and  Moral  Traits 

The  possibility  of  analyzing  mental  traits  into  unit  characters 
and  controlling  their  appearance  in  the  human  species  by  breeding 
so  as  to  get  the  determiners  of  desired  traits  established  in  all 
the  germs,  and  to  get  all  the  germs  freed  from  the  determiners 
of  undesired  ones,  is  very  attractive.  If  bad  temper  in  man  is 
as  simple  a  compound  of  unit  characters  as  hornedness  in  cattle  or 
color  in  mice,  we  may  hope  to  raise  a  race  of  assuredly  good- 
tempered  men! 

It  has  been  suggested  [Davenport  'lo,  p.  I4f.]  that  imbecility 
is  a  unit  character,  depending  on  the  absence  of  a  certain  deter- 
miner. "  That  imbecility  is  due  to  the  absence  of  some  definite 
simple  factor  is  indicated  by  the  simplicity  of  its  method  of  inherit- 
ance. Two  imbecile  parents,  whether  related  or  not,  have  only 
imbecile  offspring.  Barr  gives  us  such  data  as  the  following  from 
his  experience.  A  feeble-minded  man  of  38  has  a  delicate  vvife 
who  in  20  years  has  borne  him  19  defective  children.  A  feeble- 
minded epileptic  mother  and  an  irresponsible  father  have  7  idiotic 
and  imbecile  children.  The  L.  family  numbers  7  persons,  both 
parents  and  all  5  children  imbecile.  Among  the  "  Family 
Records  "  I  have  been  collecting  there  occurs  the  R.  family  where 
A   (insane)   marries  in  succession  two  mentally  weak  wives  and 

has    13   children,   all   mentally   weak In   a   case 

described  by  Bennett,  a  defective  father  and  an  imbecile  mother 
have  7  children  all  more  or  less  mentally  and  morally  defective. 
There  is,  so  far  as  I  am  aware,  no  case  on  record  where  two 
imbecile  parents  have  produced  a  normal  child." 

I  fear,  however,  that  the  inheritance  of  imbecility  will  be  found 
by  no  means  so  simple  as  Dr.  Davenport  hopes.  If  it  were  due 
to  the  absence  of  some  definite  simple  factor,  there  should  be 
some  clear  division  of  intellects  into  those  from  germs  totally 
lacking  this  determiner,  those  from  germs  having  a  single  deter- 
miner, and  those  from  germs  having  the  normal  double  determiner. 
There  is  certainly  no  such  clear  division  and  it  is  very  doubtful 
if  there  is  any  greater  division  between  imbecile  and  not  quite 
imbecile,  than  between  the  latter  and  an  intellect  a  trifle  higher, 
and  so  on  up  to  and  beyond  individuals  of  average  intellect.  The 
condition  of  the  children  in  the  families  mentioned  above  should 
certainly  be  made  the  subject  of  very  careful  measurements  before 


The  Influence  of  Immediate  Ancestry  or  Family        103 

it  is  assumed  that  they  are  all  sharply  distinct  from  the  offspring 
of  parents  whose  germs  possess  the  '  intelligence '  determiner. 
Rough  estimates  are  very  unsafe. 

It  seems  probable  that  two  imbecile  parents  produce  widely 
varying  offspring  including  some  more  imbecile  than  they  and 
some  far  higher  than  they  on  the  intellectual  scale.  Richardson 
['02,  p.  9]  writes:  "Imbeciles  who  have  been  impregnated  by 
imbeciles  have  produced  normal  children  as  a  rule  in  the  few 
cases  recorded,  and  in  my  experience  I  know  of  a  case  where  a 
feeble-minded  boy  of  eighteen  impregnated  a  feeble-minded  girl 
of  sixteen,  producing  a  perfectly  normal  child." 

Mental  traits  are  certainly  not  as  a  rule  unit  characters  or  the 
results,  each  of  two  or  three  cooperating  unit  characters.  On  the 
contrary,  most  of  them  seem  to  be  the  results  of  very  many  unit 
characters.  It  will  be  shown  in  Chapter  VIII  that  no  case  is 
known  of  a  mental  trait  appearing  in  three  sharply  defined  degrees, 
— o,  moderate,  and  full  amount, — with  clear  gaps  between, 
as  a  unit  character  should.  Almost,  if  not  quite,  all  mental  traits, 
so  far  as  they  are  due  to  original  nature,  appear  in  many  different 
degrees,  each  varying  very  slightly  from  the  next.  But  this 
gradation  in  a  trait's  amount  necessitates  the  existence  of  many 
determiners  to  produce  it,  if  it  is  to  be  produced  by  determiners 
that  do  not  themselves  vary  greatly  in  force.  So,  for  intellectual 
and  moral  traits,  the  task  of  analysis  into  unit  characters  and 
attribution  to  invariable  determiners  seems  likely  to  be  very,  very 
difficult. 

It  is  not  necessary  to  decide  whether  the  facts  of  mental  inherit- 
ance can  be  explained  by  constant  determiners  or  require  variable 
determiners ;  nor  whether,  if  the  latter  be  the  case,  two  variable 
determiners  of  the  same  trait  may  blend.  The  question  must  be 
left  for  investigation  by  students  from  both  sides.  The  chief 
present  value  of  the  IMendelian  facts  and  hypotheses  to  students 
of  intellectual  and  moral  traits  is  as  an  encouragement  to  the 
more  exact  description  and  analysis  of  the  original  natures  of 
individual  men,  and  to  more  exact  measurements  of  individual 
resemblances. 


CHAPTER  VI 
The  Influence  of  Maturity 

No  competent  student  doubts  that  in  certain  mental  traits 
maturity  or  inner  mental  growth  causes  one  individual  to  differ 
year  by  year  from  his  former  self,  irrespective  of  all  training. 
The  same  force  necessarily  accounts  for  some  of  the  differences 
found  between  children  of  different  degrees  of  mental  maturity. 
If  by  a  miracle  a  hundred  children  could  be  found  who  were  alike 
in  sex,  ancestry  and  training,  but  w^ho  were  divided  into  two 
groups  by  a  dift'erence  in  the  extent  to  which  the  original  impetus 
to  mental  development  had  run  its  course,  the  groups  would  differ, 
in  at  least  certain  traits,  in  accordance  with  this  difference  in 
stage  of  growth  or  maturity. 

About  the  magnitude  of  the  influence  of  maturity  there  is, 
however,  a  wide  range  of  opinion,  from  that  which  would  expect 
children  in  the  same  stage  of  growth  to  be  all  closely  alike  and 
all  very  different  from  children  in  a  later  stage  of  growth,  regard- 
less of  differences  in  their  ancestry  and  training,  to  that  which 
would  expect  children  of  the  same  ancestry  and  training  to  be 
all  very  much  alike,  regardless  of  dift'erences  in  stage  of  growth. 

The  study  of  the  facts  is  made  difficult  by  the  absence  of  any 
exact  measure  of  maturity,  that  is,  of  the  extent  to  which  the 
original  impetus  to  mental  development  has  run  its  course.  Length 
of  life  is  the  measure  which  has  been  used,  but  chronological 
age  is  not  identical  wdth  physiological  maturity  and  neither  of 
these  two  is  identical  with  mental  maturity.  An  individual's 
degree  of  mental  maturity  cannot  be  inferred  from  his  age.  In 
the  long  run,  however,  the  central  tendencies  of  children  of  the 
ages  6,  7,  8,  etc.,  will  represent  the  central  tendencies  of 
successive  stages  in  mental  growth.  And  in  any  case  such 
comparisons  of  children  at  different  ages  are  the  only  measure- 
ments available  in  support  of  conclusions  about  the  influence  of 
maturity. 

(104) 


The  Influence  of  Maturity  105 

Changes  in  Mental  Traits  with  Age 

Some  of  the  best  known  and  most  commended  studies  in 
educational  psychology  deal  with  the  differences  in  mental  traits 
between  children  of  different  ages.  The  most  extensive  and  also 
the  most  painstaking  study  of  this  sort  is  Dr.  Gilbert's  Researches 
on  the  Physical  and  Mental  Development  of  School  Children 
['94].  A  fairly  careful  examination  of  its  method  and  results 
will  be  our  best  introduction  to  the  general  problems  of  the  chapter. 

Dr.  Gilbert  made  a  number  of  measurements  of  both  physical 
and  mental  traits  in  boys  and  girls  from  six  to  seventeen  years  old. 
The  mental  traits  were  : 

1.  Delicacy  of  discrimination  of  weight  ('Muscle-Sense'). 
(Ten  weights,  identical  in  shape  and  size,  but  weighing  84  grams, 
86  grams,  etc.,  were  set  before  a  child  and  he  was  asked  to  sort 
out  all  those  which  seemed  to  him  to  be  of  exactly  the  same  weight 
as  the  82-gram  one  (which  was  marked  by  a  white  dot).  Delicacy 
of  discrimination  was  then  measured  inversely  by  the  difference  in 
weight  of  the  weights  thought  to  be  identical.) 

2.  Delicacy  of  discrimination  of  color.  (A  series  of  reds  varying 
progressively  in  darkness  were  used  as  the  weights  were  in  i.) 

3.  Force  of  suggestion.  (Measured  by  the  amount  a  child  over- 
estimated a  weight  small  in  size  compared  with  the  same  weight 
made  much  larger.) 

4.  Voluntary  motor  ability.  (The  number  of  taps  made  with 
the  finger  in  45  seconds.) 

5.  Fatigue.  (Let  T=  the  number  of  taps  made  in  the  first 
5  seconds  of  a  trial  for  45  seconds.     Let  L  =  the  number  of  taps 

"X L 

made  in  the  last  5  seconds.     Let  F=  — 7^ — •    F  was  the  measure 

of  fatigue  used.) 

6.  Reaction  time.  (Measured  by  the  time  taken  to  see  a  signal 
and  react  by  pressing  down  a  key.) 

7.  Reaction  with  discrimination  and  choice.  (Measured  by  the 
time  taken  to  see  that  the  signal  was  blue  and  not  red  and  to  react 
by  pressing  down  a  key.) 

The  essential  results  of  Gilbert's  study  are  given  in  Table  10. 
It  tells  with  fair  accuracy  the  median  ability  of  every  such  group 
as  '  girls  from  9  years  o  months  to  9  years  1 1  months  inclusive,' 
and  the  variability  of  every  such  group   in   four   of  the  traits 


106  Educational  Psychology 

measured.    In  three  traits  the  variability  is  given  only  for  boys  and 
girls  together. 

TABLE  lo. 

The  Central  Tendencies  and  Variabilities  op  Children  of  Dif- 
ferent Ages  in  Discrimination  of  Weight,  Discrimination  of  Shades 
OF  Red,  Resistance  to  the  Size-Weight  Illusion,  etc. 

M.  V.  =  in  all  cases  the  average  deviation  of  the  individual  children  from 
the  median  child  of  that  year-age. 

B  =  in  all  cases,  boys. 

G=  in  all  cases,  girls. 

D  wt.  =:  the  number  of  grams  difference  required  in  order  that  the 
median  child  should  perceive  the   difference. 

D  col.  =  the  smallest  number  of  differences  (not  objectively  defined) 
required  in  order  that  the  median  child  should  perceive  the  difference. 
For  a  statement  of  the  nature  of  the  differences  see  Gilbert,  '93,  p.  42  f. 

H  —  the  median  difference  in  grams  between  the  two  weights  (of  equal 
size)  chosen  as  equal  respectively  to  two  blocks,  each  weighing  55  grams 
and  being  2.8  cm.  thick,  but  being  2.2  cm.  and  8.2  cm.   in  diameter. 

T  =  the  number  of  taps  made  in  the  first  S  seconds  of  45  by  the  median 
child. 

T— L 

F-       /p  -  (L  bemg  the  number  of  taps  made  in  the  last  5  seconds  of 

45  by  the  median  child). 

Rs  =  the  time,  in  thousandths  of  a  second,  between  the  movement  of  a 
disc  and  the  making  of  a  contact  by  a  child  who  is  instructed  to  press 
down  the  key  as  soon  as  he  sees  the  disc  move :  the  median  child's  time. 

Rd  =  the  time  to  see  a  blue  surface  and  react  to  it  as  for  Rs.  no 
reaction  being  permissible  if  the  surface  shown  was  red  instead  of  blue. 


Muscle-Sense 

Age. 

Dwt.iB+G) 

MViB+G) 

Dwt.{B) 

Dwt.{G) 

6 

14.8 

5-2 

13.0 

16.8 

7 

136 

4-4 

13.2 

13.2 

8 

11. 4 

4.6 

12.2 

II  .0 

9 

10. 0 

4-4 

10.2 

10. 0 

10 

8.8 

4-4 

8.6 

9.2 

II 

8.6 

3-8 

10.2 

7.6 

12 

7.2 

30 

7.6 

7.6 

13 

5-4 

30 

6.0 

5-6 

14 

5-6 

30 

5-2 

7.2 

15 

6.8 

2.2 

6.2 

7.2 

16 

6.6 

2-4 

6.0 

6.8 

17 

5-8 

2.6 

6.0 

6.4 

The  Influence  of  Maturity 


T07 


Sensitiveness  to  Color-differences 


Age. 

Dcol.{B-^G) 

MV{B+G) 

Dcol.iB) 

Dcol.{G) 

6 

9.6 

1.8 

8.3 

9.6 

7 

9 

0 

2 . 1 

8.3 

9.6 

8 

8 

3 

2-3 

9.6 

7.0 

9 

6 

3 

2  .2 

6.1 

6.6 

10 

5 

4 

1-9 

6.0 

5-2 

II 

5 

4 

1-7 

6.0 

4-9 

12 

5 

I 

1-5 

4.8 

51 

13 

4 

6 

1-7 

5-2 

41 

14 

4 

7 

1-4 

4.8 

4.6 

15 

4 

4 

I .  I 

4.1 

4-6 

16 

4 

3 

1-3 

4-3 

4.0 

17 

3 

9 

1-4 

4.0 

4-9 

Force  of  Suggestion 


Age. 

H{B+G) 

MV{B+G) 

H{B) 

//(( 

-) 

6 

42  .0 

17.0 

43-5 

42 -5 

7 

45 

0 

155 

43-5 

43 

5 

8 

47 

5 

135 

45  0 

49 

5 

9 

50 

0 

10.5 

50.0 

49 

5 

10 

43 

5 

12.5 

40.0 

44 

0 

II 

40 

0 

"•5 

38.5 

40 

0 

12 

40 

5 

9.0 

38.0 

41 

0 

13 

38 

0 

9.0 

370 

38 

0 

14 

34 

5 

9-5 

31.0 

33 

5 

15 

35 

0 

10.5 

330 

38 

0 

16 

34 

5 

lO.O 

32.0 

38 

5 

17 

27 

0 

12  .0 

25.0 

31 

0 

Voluntary  Motor  Ability 


Age.      T(fi+G)      MV{B^G)    T{B) 


6 

20.8 

7 

22.5 

8 

24.4 

9 

254 

10 

27.0 

II 

29.0 

12 

29.9 

13 

28.9 

14 

30.0 

15 

311 

16 

32.1 

17 

33-8 

MV{B) 
2-5 

2-7 

3-4 

2-5 

2.6 
3-2 

3-1 
30 

3-2 
2.6 

3-0 
2-4 


T{G) 
19.7 
21.2 

239 
25.0 
26.9 
27.8 
29.6 
28.1 
28.0 
29.8 
31.8 
315 


MVifi) 

2-5 
2-5 

2  .2 
2.9 
.8 
.0 
.0 
■3 
•4 
.2 

■4 
■3 


io8 


Educational  Psychology 


Fatigue 


Age. 

F(fi+G) 

MViB+G) 

F(i?) 

MV{B) 

F(G) 

MV{G) 

6 

21.4 

8.1 

22.8 

9-4 

21.3 

7.0 

7 

21 .0 

8 

9 

22 

5 

9 

7 

20.2 

6 

7 

8 

24.0 

7 

3 

24 

7 

8 

3 

233 

7 

I 

9 

21 .0 

7 

I 

22 

5 

6 

7 

20.7 

7 

8 

lO 

22.0 

7 

5 

22 

7 

7 

8 

19.0 

7 

I 

II 

20.0 

6 

2 

20 

3 

6 

5 

18.0 

5 

5 

12 

16.0 

6 

3 

18 

0 

6 

0 

14.0 

6 

7 

13 

14  5 

6 

4 

15 

8 

6 

7 

147 

5 

8 

14 

14.0 

6 

5 

17 

8 

6 

2 

12.0 

6 

I 

15 

12.7 

5 

8 

13 

8 

4 

9 

"■5 

5 

7 

i6 

147 

5 

2 

15 

3 

4 

6 

II. 7 

5 

6 

17 

13-8 

5 

3 

14 

5 

6 

3 

135 

4 

3 

Reaction 

Time 

Age. 

Rs(B-\-G) 

MV(B  +  G) 

i?.(5) 

MF(5) 

Rs{G) 

MF(G) 

6 

295 

50 

282 

46 

295 

54 

7 

292 

55 

267 

46 

315 

52 

8 

262 

39 

245 

39 

260 

31 

9 

250 

41 

243 

54 

255 

49 

lO 

215 

36 

210 

26 

225 

43 

II 

195 

34 

185 

31 

206 

34 

12 

187 

31 

178 

27 

198 

35 

13 

187 

30 

178 

29 

205 

35 

14 

180 

29 

180 

30 

187 

30 

15 

172 

27 

167 

23 

189 

27 

i6 

155 

23 

147 

16 

172 

26 

17 

155 

3. 

5 

1/ 

i7 

K 

? 

163 

2< 

3 

Reaction  with  Discrimination  and  Choice 


6 

525 

60 

7 

530 

81 

8 

478 

65 

9 

450 

68 

10 

410 

49 

II 

385 

58 

12 

370 

55 

13 

395 

58 

14 

365 

49 

15 

335 

49 

16 

325 

43 

17 

312 

40 

535 

53 

490 

88 

480 

57 

445 

63 

400 

49 

387 

58 

385 

60 

360 

51 

367 

45 

3" 

55 

315 

39 

305 

35 

ld{G) 

MV{G) 

510 

65 

528 

94 

475 

55 

460 

72 

415 

45 

388 

57 

370 

49 

415 

55 

355 

54 

345 

38 

350 

39 

315 

44 

The  Influence  of  Maturity  109 

Just  what  do  these  median  abihties  of  Table  10  mean?  Just 
what  do  the  differences  between  those  for  six  and  seven,  seven 
and  eight,  etc.,  tell  us  about  the  development  of  mental  traits  in 
life?  Just  what  do  we  learn  about  human  nature  from  these 
comparisons  of  the  capacities  of  children  of  different  ages  ? 

It  is  clear  that  an  alteration  in  any  mental  trait  in  any  individual 
with  age  might  be  due  to  the  mere  maturing  of  some  characteristic 
of  original  nature  or  might  be  the  creation  of  some  environmental 
force.  The  educational  inferences  would  be  exactly  opposite  in 
the  two  cases.  In  the  former  we  should  say :  This  change  comes 
as  a  gift  from  nature  which  we  may  not  be  able  to  refuse  without 
damaging  general  growth.  It  is  given  as  the  partial  basis  and 
starting  point  for  education.  We  do  not  have  to  try  to  get  it. 
In  the  latter  case  we  should  say :  This  change  comes  as  the 
earnings  of  training.  It  is  a  product  of  education.  With  a 
different  training  it  might  be  absent.  We  may  lack  or  possess  it 
as  we  choose. 

Moreover,  in  the  case  of  many  measurements  of  mental  traits, 
for  instance  those  quoted,  the  change  due  to  an  individual's  age 
would  be  possibly  due  not  only  to  the  maturing  of  the  trait  or 
the  influence  of  training  upon  it,  but  also  to  the  influence  of  both 
maturity  and  training  upon  the  ability  to  understand  and  the  wish 
to  follow  instructions  and  the  ambition  to  do  well  in  tests.  This 
complex  of  traits  we  may  call  general  ability  in  tests.  It  is  even 
conceivable  that  the  last  factor  was  the  sole  cause  of  all  the 
changes  quoted  above. 

As  a  matter  of  fact  all  three  of  these  factors  are  involved  in 
most  of  the  changes  of  mental  traits  with  age.  Even  if  the  changes 
are  due  directly  to  outside  forces,  in  the  form  of  the  experiences  of 
life  and  training,  maturity  may  still  count  as  a  force  cooperating 
with  these  or  furnishing  the  conditions  in  the  individual  which 
permit  their  action  on  him  to  produce  the  mental  changes  in 
question.  On  the  other  hand,  mere  inner  growth,  no  matter  how 
potent,  requires  usually  some  stimuli  from  without.  A  child 
grows  mentally  in  some  kind  of  a  world  of  experience,  forming 
some  habits.  Only  in  thought  can  the  contribution  of  his  inner 
impulsions  be  separated  off  from  the  contribution  of  the  outside 
stimuli  by  which  the  inner  impulsions  are  roused  to  action.  Further- 
more, a  mental  test  with  children  almost  always  measures  some- 


no  Educational  Psychology 

what  general  powers  of  comprehension  as  well  as  the  special  power 
of  sensation,  memory  or  the  like  that  is  its  ostensible  object. 

Hence  mere  knowledge  of  age  differences  in  a  mental  trait, 
without  knowledge  of  how  their  causation  is  distributed  amongst 
these  three  factors,  does  not  allow  us  to  estimate  the  amount  of 
influence  of  maturity  in  determining  an  individual's  status  in 
respect  to  the  trait.  The  total  age  change  must  at  least  be  divided 
between  mere  maturity  and  the  added  training  which  has  accom- 
panied maturity.  Until  this  is  done  we  cannot  progress  far 
beyond  the  vague  commonplaces  of  common  observation. 

TJie  Difficulties  in  Inferring  Changes  in  Individuals  zvith  Age 
from  Differe,nces  Between  Old  and  Young  Indidivucls 

So  far  upon  the  supposition  that  by  changes  in  mental  traits 
with  age,  we  mean  changes  in  the  same  individuals  measured  at 
different  ages.  The  average  change  would  then  be  the  average 
of  the  changes  in  all  the  individuals  studied.  But  in  the  studies 
that  have  been  reported,  the  difference  between  the  figures  for, 
say,  ten  and  eleven  years,  is  not  the  average  of  the  changes  of 
all  the  individuals  studied  and  need  not  in  any  real  way  describe 
them. 

For  (i)  the  difference  between  the  average  of  a  group  at  ten 
and  of  the  same  group  at  eleven  years  does  not  describe  the  real 
individual  changes;  and  (2)  when  we  measure  ten- and  eleven- 
year-olds  as  we  find  them  in  school  or  elsewhere,  we  can  not  be 
sure  that  the  eleven-year-olds  represent  what  the  ten-year-olds  will 
become. 

The  first  point  will  be  made  clear  by  the  following  illustration. 
Suppose  that  eighteen  boys  showed  at  the  age  of  ten  and  a 
half  years  the  abilities  in  some  mental  trait  denoted  by  the 
measures  in  the  first  column  and  made  the  gains  during  the  next 
year  shown  by  the  figures  in  the  second  column,  their  consequent 
records  at  eleven  and  a  half  years  being  given  in  the  third  column. 
(Case  I.) 

If  instead  of  this  complete  record  we  had  simply  the  figures : 
10I4  years,  Av.  5.94;  nl/^  years,  Av.  8.16;  Change  in  average 
ability,  2.22,  we  should  lack  the  essential  features  of  our  fact ; 
viz.,  (i)  the  variability  of  the  changes  and  (2)  the  antagonism 
between  ability  at  ten  and  a  half  years  and  growth  during  the 


Case  2 

Ability 

Ability 

at  loK 

Change 

at  iiK 

2 

o 

2 

2 

o 

2 

3 

I 

4 

4 

o 

4 

4 

I 

5 

5 

3 

8 

5. 

I 

6 

6 

I 

7 

6 

I 

7 

6 

3 

9 

6 

3 

9 

7 

I 

8 

7 

4 

II 

7 

4 

II 

8 

3 

II 

9 

4 

13 

9 

5 

14 

II 

5 

i6 

5-94 

2  .22 

8.i6 

T/i^  Influence  of  Maturity  iii 

Case  I 
Ability  Ability 

at  io>3        Change        at  ii>^ 

2  5  7 
257 

3  4  7 

4  3  7 
448 

5  4  9 
5  I  6 
639 
639 
617 
617 
7  I  8 
7  3  10 
7  I  8 
808 
9  I  10 
909 

II  O         II 

Avg.  5.94     2.22      8.16     Avg. 

next  year.  There  is  an  almost  inevitable  tendency,  when  a  single 
figure  is  given  to  represent  change,  to  fancy  that  all  children  show 
exactly  or  nearly  that  amount  of  change.  This  is  of  course  never 
true.  Rate  of  change  as  well  as  absolute  ability  is  variable.  And 
it  is  precisely  in  relating  the  different  degrees  of  progress  found 
in  individuals  to  their  original  capacities  and  individual  circum- 
stances, that  educational  insight  will  accrue.  The  real  individual 
changes  may  often  prove  to  be  a  partial  function  of  the  amount 
of  ability  already  acquired,  as  in  our  illustration.  The  mere 
change  in  average  ability  given  above  could  have  come  as  well 
from  a  condition,  shown  in  Case  2,  just  opposite  in  this  respect 
to  that  of  Case  i. 

In  Case  2,  the  better  a  boy  is  at  ten  and  a  half  years  the  more  he 
gains ;  whereas  in  Case  i ,  the  better  he  was  the  less  he  gained.  Case 
2  would,  I  venture  to  prophesy,  be  the  fact  in  the  progress  with 
age  of  real  mental  efficiency,  while  with  physical  growth  from 
thirteen  to  eighteen  we  should  have  something  like  Case  i,  the 
children  who  had  matured  early  and  so  attained  high  stations  in 
stature  growing  little,  while  those  who  matured  slowly  would  keep 
on  growing  at  a  fair  rate.    In  brief,  the  growth  of  averages  does 


112  Educational  Psychology 

not  accurately  describe,  and  may  positively  misrepresent,  the  real 
growth  of  the  individuals  in  the  group. 

Our  second  point  was  that  the  eleven-year-olds  tested  need  not 
represent  what  the  ten-year-olds  would  become.  The  average 
changes  stated  in  the  quotations  at  the  beginning  of  this  chapter 
were  obtained  from  facts  like  the  following:  Ten-year-olds 
A,  B,  C,  D,  E,  F,  G,  H,  etc.,  give  an  average  x ;  eleven- 
year-olds,  L,  M,  N,  O,  P,  etc.,  give  an  average  y.  The 
change  in  average  ability  is  y  -  x.  The  individuals  of  the  two 
groups  not  being  identical,  the  chance  is  given  for  the  fallacy  of 
selection  to  run  riot.  The  eleven-twelve-year-olds  certainly 
represent  only  those  ten-eleven-year-olds  who  will  live ;  in  any  test 
given  in  schools  they  represent  only  the  ten-eleven-year-olds  who 
will  continue  in  that  type  of  school.  Now  if  one  measures  a  mental 
trait  in  elementary  school  children  he  gets  for  different  ages  some- 
thing like  the  following  figures: — 12  year-olds,  100;  13-year-olds, 
90;  14-year-olds,  70;  15-year-olds,  30. 

Nobody  can  imagine  that  the  fifteen-year-olds  here  would  give 
anything  like  a  fair  sampling  of  what  the  twelve-year-olds  would 
become.  The  brightest  twelve-year-olds  pass  out  of  the  grammar 
school  before  they  are  fifteen.  Some  mental  defectives  leave  for 
special  institutions.  Some  moral  defectives  leave  for  reform 
schools  or  the  free  life  of  thievery  and  trampdom.  Some  chil- 
dren of  very  poor  parents  go  to  work.  If  we  fill  up  our  quota 
of  fifteen-year-olds  by  adding  70  from  high  school  pupils  we 
jump  from  the  frying  pan  into  the  fire,  for  these  are  a  selection 
of  the  brighter,  the  more  ambitious,  those  whose  parents  are 
fairly  well  off  financially  and  are  intellectually  inclined. 

I  conclude,  therefore,  that  the  development  of  mental  traits  with 
age  has  not  been  and  can  not  be  adequately  measured  by  such 
studies  as  those  quoted.  To  measure  it  we  must  repeat  measure- 
ments upon  the  same  individuals  and  for  all  purposes  of  infer- 
ence preserve  intact  each  of  the  individual  changes.  In  connec- 
tion with  each  of  them  account  must  be  taken  of .  the  training 
which  the  individual  in  question  has  undergone. 

What  measurements  we  do  have  may  serve,  however,  to  cor- 
rect two  errors  of  common  opinion.  The  notion  that  the  increases 
in  ability  due  to  a  given  amount  of  progress  toward  maturity 
are  closely  alike  for  all  children  save  the  so-called  ''  abnormally 
precocious  "  or  "retarded "  is  false.     The  same  fraction  of  the 


The  Influence  of  Maturity  113 

total  inner  development,  from  zero  to  adult  ability,  will  produce 
very  unequal  results  in  different  children.  Inner  growth  acts 
differentially  according  to  the  original  nature  that  is  growing. 

The  notion  that  maturity  is  the  main  factor  in  the  differences 
found  amongst  school  children,  so  that  grading  and  methods  of 
teaching  should  be  fitted  closely  to  'stage  of  growth,'  is  also  false. 
It  is  by  no  means  very  hard  to  find  seven-year-olds  who  can  do 
intellectual  work  at  which  one  in  twenty  seventeen-year-olds  would 
fail.  Although  the  influence  of  inner  growth  in  causing  individual 
differences  cannot  be  measured  from  the  data  at  hand,  an  upper 
limit  for  it  can  be  set.  Take  discrimination  of  weight  as  a  sample 
case.  Since  early  age  differences  are  in  part  due  to  training  and 
since  training  acts  here  in  the  same  direction  as  does  maturity, 
the  average  inner  growth  from,  say,  ten  to  seventeen  must  produce 
less  than  the  average  difference  found  between  ten-year-olds  and 
seventeen-year-olds.  Since,  in  Gilbert's  study,  the  seventeen-year- 
olds  and  ten-year-olds  both  come  from  school  pupils,  including 
pupils  in  the  high  school,  the  seventeen-year-olds  represent  at 
least  as  high  ranking  pupils  in  mental  respects  as  the  ten-year-olds 
would  become.  So  the  effect  of  average  inner  growth  from  ten 
to  seventeen  is  at  the  outside  a  reduction  in  the  least  noticeable 
difference  from  8.8  to  5.8  grams.  But  many  ten-year-olds  noticed 
a  difference  of  5.8  grams  or  less.  Gilbert's  4.4  (for  the  average 
deviation  of  the  individual  ten-year-olds  from  their  C.  T.)  would 
put  30  per  cent  of  them  above  the  average  seventeen-year-old 
unless  the  distribution  of  individual  differences  among  the  ten- 
year-olds  is  markedly  eccentric.  And  within  the  ten-year-olds 
there  is  a  range  of  variation  at  least  five  times  as  great  as  that 
between  the  average  ten-year-old  and  the  average  seventeen-year- 
old.  The  range  cannot  be  less  than  four  times  4.4  g.  unless  the 
distribution  (surface  of  frequency)  is  of  a  form  never  found  in 
measurements  of  discrimination  of  weight.  Hence  even  the  top- 
most limit  for  the  average  effect  of  these  seven  years'  maturity  is 
surely  less  than  one  sixth  of  the  effect  of  the  extreme  dift'erences 
in  ancestry  and  training  upon  children  of  the  same  age. 


CHAPTER  VII 

The  Influence  of  the  Environment 

Difficulties  in  Estimating  the  Amount  of  Influence  of  the 
Environment 

The  questions  suggested  by  the  title  of  this  chapter  include 
the  effects  on  individuals  of  every  environmental  force,  including 
all  the  agencies  for  intellectual  and  moral  education.  Precise 
quantitative  answers  can  be  given  to  hardly  any  of  them. 

Theoretically,  there  is  no  impossibility.  Once  we  have  esti- 
mated the  original  nature  of  a  man  or  group  of  men,  we  have 
simply  to  note  the  mental  changes  consequent  upon  this  or  that 
change  in  climate,  food,  school  training,  friendship,  sermon,  occu- 
pation, etc.  Practically,  the  complexity  of  the  action  of  physical 
and  human  influences  upon  intellect  and  character  hampers  scien- 
tific study  and  favors  guesswork.  The  environment  includes  a 
practical  infinitude  of  different  causes ;  these  act  differently  upon 
different  types  of  original  nature  and  at  different  ages  and  with 
different  cooperating  circumstances ;  in  many  cases  their  action 
is  very  complex  and  must  be  observed  over  long  intervals  of 
time.  Indeed  it  has  been  common  to  deny  even  the  possibility 
of  a  science  of  the  dynamics  of  human  nature  and  to  remain 
content  with  the  haphazard  opinions  of  novelists,  proverb  makers 
and  village  wise  men. 

Moreover,  it  is  only  by  the  utmost  ingenuity  and  watchfulness 
that  studies  of  changes  in  human  nature  can  be  freed  from  a  char- 
acteristic fallacy — that  of  attributing  to  training  facts  which  are 
really  due  to  original  nature  or  to  selection.  For  instance,  col- 
lege graduates  are  found  to  have  a  much  greater  likelihood  of 
being  elected  to  Congress  than  other  men  have.  Therefore  it 
is  said  that  a  college  education  causes  to  some  extent  political  suc- 
cess. But  it  is  clear  that  even  before  they  went  to  college  the 
group  of  youth  who  did  go  were  different  from  those  who  did  not. 

(114) 


The  Influence  of  the  Environment  115 

Their  later  election  to  Congress  may  as  well  have  been  due  to 
the  mental  traits  which  they  possessed  by  birth  or  otherwise  and 
which  caused  their  inclusion  in  the  class  '  boys  who  go  to  college  ' 
as  to  any  changes  produced  in  them  by  the  college  training  itself. 
In  other  words,  that  they  were  the  class  selected  by  the  college 
is  as  important  a  fact  as  that  they  were  the  class  trained  by  it. 

Again  it  is  said :  "  Who  can  doubt  the  enormous  disciplinary 
value  of  the  study  of  Latin  and  Greek  when  we  see  the  admirable 
intellects  of  the  men  so  trained  in  the  English  universities?" 
But  being  born  from  the  class  whose  children  go  to  the  university 
of  itself  ensures  to  an  individual  uncommon  mental  ability. 

To  avoid  this  confusion  of  causes  which  train  with  those  which 
select  is  extremely  hard.  Any  class  of  individuals  studied  because 
they  have  been  subjected  to  a  certain  training  is  almost  sure  to 
be  a  class  not  only  trained  by  but  also  selected  by  that  training. 
Suppose  that  one  wishes  to  study  the  influence  of  a  high-school 
course,  or  that  of  the  classical  as  opposed  to  the  scientific  course, 
or  that  of  training  in  independent  research,  or  that  of  immoral 
surroundings.  High  school  graduates  are  but  one  fifth  of  gram- 
mar school  graduates ;  and  no  one  would  claim  that  they  repre- 
sent an  entirely  random  picking  therefrom.  They  are  surely 
selected  for  better  birth,  better  abilities  and  better  ideals.  Again, 
in  most  high  schools  the  graduate  of  the  classical  course  represents 
not  only  a  different  training,  but  also  a  different  selection,  com- 
monly a  superior  selection.*  So  also  scientific  men  are  a  class 
resulting  not  only  from  the  training  given  by  research  work,  but 
also  from  the  selection  of  those  eager  to  do  and  fitted  to  do  that 
work.  Children  brought  up  in  a  morally  bad  environment  are 
almost  sure  to  be  of  morally  inferior  ancestry.  The  ordinary 
arrangement  of  social  and  educational  careers  rarely  presents 
us  with  convenient  cases  of  similar  natures,  some  with,  some  with- 
out, the  form  of  training  under  consideration. 

The  difficulty  of  eliminating  the  influence  of  selection  is  no 
excuse  for  its  neglect.  Yet  one  may  hunt  through  thousands  of 
pages  of  discussions  of  the  influence  of  certain  studies,  school 
systems,  schemes  of  culture,  religious  beliefs,  etc.,  without  finding 
a  hint  of  its  recognition. 

Either  because  of  the  general  complexity  of  environmental  in- 
fluences  upon   any   mental   trait   and    the   mixture   of   selective 

*This  apparently  is  becoming  less  common  every  year. 


ii6  Educational  Psychology 

with  formative  influences  or  because  of  the  infrequency  of  scien- 
tific habits  and  ideals  in  students  of  sociology  and  education, 
there  are  few  facts  of  sufficient  security  and  precision  to  be 
quoted.  Only  rarely  has  educational  science  progressed  beyond 
the  reasoned  opinions  of  more  or  less  capable  judges.  We  have 
our  beliefs  about  the  causal  relations  between  a  hot  climate  and 
indolence,  necessity  and  invention,  lack  of  parental  control  and 
crime,  religious  training  and  morality,  etc.,  but  we  can  not  be 
said  to  know  these  influences  with  adequate  surety  or  to  have 
any  knowledge  whatever  of  their  precise  amount. 

A  refusal  to  believe  insecure  opinions  about  the  influence  of 
differences  in  training  in  producing  differences  in  human  indi- 
viduals does  not  at  all  imply  disbelief  in  their  influence.  Such 
w^ould  be  absurd.  When  the  original  natures  are  the  same,  every 
difference  that  the  individuals  later  show  must  be  due  to  differ- 
ences in  the  outside  forces  operating  upon  them.  And  any  differ- 
ence in  outside  forces  always  has  its  effect.  No  man  is  left  un- 
changed by  even  the  very  least  of  the  environmental  forces  that 
act  upon  him.  Men  are  the  creatures  of  circumstance.  But  they 
are  creations  whose  final  patterns  are  determined  in  part  by  sex, 
race,  ancestry  and  conditions  of  origin.  Circumstances  alter 
natures,  but  the  alterations  vary  with  the  nature  altered.  It  is 
precisely  because  common  opinions  have  thought  verbally  in  terms 
of  '  man-training-product  of  training ' ,  instead  of  concretely  in 
terms  of  'men-training-products, — each  of  an  individual's  nature 
in  interaction  zvith  his  training ' ,  that  a  sound  science  of  the  in- 
fluence of  the  environment  has  hardly  been  begun. 

One  of  the  best  services  such  a  science  can  render  is  to  guard 
its  students  against  such  verbal  plausibilities.  For  example, 
knowledge  is  not  proportional  to  opportunity  in  the  sense  that  an 
individual's  degree  of  knowledge  can  be  foretold  from  his  degree 
of  opportunity.  Wealth  does  not  create  wealth  in  the  sense  that 
what  a  man  will  have  can  be  estimated  from  what  he  now  has. 
A  good  home  does  not  make  good  children  in  the  sense  of  doing 
so  always  and  in  proportion  to  its  goodness.  Being  treated  like 
slaves  may  not  debase  all  and  never  debases  all  alike.  The  product 
of  the  environment  is  always  a  result  of  two  variables,  it  and  the 
man's  nature. 

Two  of  the  corollaries  of  this  axiom  are  of  special  significance. 
The  first  is  that  the  environmental  stimulus  adequate  to  arouse  a 


The  Influence  of  the  Environment  117 

certain  power  or  ideal  or  habit  in  one  man  may  be  hopelessly 
inadequate  to  do  so  in  another.  Washing  bottles  in  a  diug-shop 
was,  if  a  common  story  is  true,  adequate  to  decide  Faraday's 
career,  and  the  voyage  on  the  Beagle  is  reputed  to  have  made 
Darwin  a  naturalist  for  life.  But  if  all  the  youth  of  the  land  were 
put  to  work  in  drug-shops  and  later  sent  on  scientific  expeditions, 
the  result  would  not  be  a  million  Faradays  and  Darwins,  or  even 
a  million  chemists  and  naturalists.  All  that  one  man  may  need 
to  be  free  is  a  vote ;  but  even  a  long  education  in  self-direction 
may  be  inadequate  for  another.  Being  told  a  few  words  suffices 
to  secure  the  habit  of  reading  in  one  child,  while  the  child  beside 
him  remains  illiterate  after  two  years  of  careful  tuition.  The 
amount  of  stimulus  required  in  some  cases  is  so  infinitesimal 
that  the  power  seems  to  spring  absolutely  from  the  man  himself. 
In  other  men  no  agency  is  found  potent  enough  to  arouse  a  trace 
of  the  desired  result. 

The  second  corollary  is  that  each  man  in  part  selects  his  own 
environment.  The  boy  turns  his  eyes  from  the  book.  Even  if 
his  eyes  attend  to  it,  his  mind  does  not.  Even  if  for  the  time  he 
lets  it  move  him,  it  may  be  disregarded  in  memory.  That  connec- 
tion which  brings  satisfaction  to  one  man  and  is  thereby  given 
power  over  him,  may  disgust  another  nature  and  so  be  repudiated 
by  it.  As  this  world's  nature  selects  for  survival  those  animals 
which  are  adapted  to  live  in  it,  so  any  individual  selects,  by  action, 
attention,  memory  and  satisfaction,  the  features  of  the  environ- 
ment which  are  to  survive  as  determinants  of  his  intellect  and 
character. 

Common  opinion  and  the  older  literature  of  sociology  and  edu- 
cation neglected  the  dift'erential  action  of  the  environment  in 
accord  with  the  nature  it  acted  on,  but  it  would  be  possible  for 
a  student,  enamored  of  the  simplicity  of  the  explanation  of  all 
men's  differences  by  differences  in  their  original  make-up,  to 
neglect  equally  obvious  facts  of  another  sort.  He  might  be 
tempted  to  claim  that,  since  the  features  of  civilization, — the 
acts,  words,  books,  customs,  and  institutions  of  men, — have  been 
invented  and  perpetuated  by  human  natures,  and  since  conse- 
quently the  environment  in  all  important  respects  is  itself  due  to 
original  nature, — therefore  original  nature  is  at  bottom  the  cause 
of  almost  all  of  human  destinies.  "  A  people  gets  as  good  govern- 
ment as  it  deserves ;  a  race  has  the  environment  its  own  nature 


ii8  Educational  Psychology 

has  found  and  chosen:  a  man  in  essential  matters  is  treated  as 
his  nature  decides."    So  he  might  carelessly  claim. 

Many  important  features  of  the  environment  are  thus  due  to 
the  original  nature  of  the  human  race  as  a  whole,  but  no  one 
man's  nature  and,  under  modern  conditions,  no  one  nation's  or 
race's  is  similarly  responsible  for  the  particular  environment  that 
it  meets.  Forces  set  in  motion  by  others  play  upon  it.  At  the 
best  it  can  select  only  negatively  by  disregard,  and  at  the  worst 
it  may  be  molded  directly  against  nature. 

Even  when  it  is  known,  and  with  some  precision,  that  a  given 
difference  is  due  to  some  difference  in  training,  there  may  be 
doubt  or  total  ignorance  as  to  what  difference  in  training  caused 
it.  And  even  when  it  is  known  that  a  given  difference  in  train- 
ing has  been  operative  and  has  produced  an  effect,  there  may  be 
doubt  or  ignorance  about  what  the  effect  is. 

Illustrations  of  the  former  case  are  abundant  in  history.  His- 
tory is  in  fact  largely  a  record  of  unexplained  changes  in  human 
nature.  Nearly  all  the  intellectual  and  moral  differences  between 
the  modern  English,  French,  or  Germans  and  their  barbarous 
ancestors  of  two  thousand  years  ago  are  due  to  differences 
in  environment.  The  original  natures  of  the  stocks  may  have 
altered  somewhat  during  that  time,  but  surely  not  much.  Our 
thoughts  and  ways  of  thinking  and  our  habits,  customs  and  ideals 
have  been  and  are  being  made  very  unlike  those  of  our  ancestors 
by  some  outside  forces.  But  what  the  forces  were  and  how  each 
contributed  to  the  result  is  not  known. 

Illustrations  of  the  latter  case  form  a  large  proportion  of  the 
facts  studied  under  the  vague  rubric  of  education.  Such  and 
such  children  have  gone  to  school,  they  have  been  taught  by  such 
and  such  teachers,  using  this  and  that  method,  at  a  cost  of  so 
many  dollars,  with  aid  of  a  material  plant  worth  so  much ;  but 
what  has  come  of  it  all,  no  cautious  thinker  would  dare  say. 
What  has  been  and  is  being  done  to  children  in  schools  is  more 
or  less  well  described  in  official  and  private  records,  but  what  hap- 
pens in  children  as  its  consequence  is  largely  unknown. 

So  much  for  the  attitude  in  which  a  student  of  human  nature 
must  approach  the  problems  of  the  effect  of  different  environ- 
ments on  identical  natures,  of  the  effect  of  the  same  environment 
on  different  natures,  and  of  the  effect  of  the  endless  different  co- 
operations of  environments  and  natures. 


The  Influence  of  the  Environment  119 

Samples  of  Measurements  of  the  Influence  of  the  Environment 

I  shall  report  four  samples  of  studies  of  the  influence  of  the 
environment  upon  intellect  and  character.  The  first  is  Galton's 
History  of  Twins  ['83],  a  study  of  the  amount  of  its  influence  in 
comparison  with  that  of  original  nature.  The  second,  from  Cat- 
tell's  Statistical  Study  of  American  Men  of  Science  ['06],  is  a 
study  of  the  effect  of  early  opportunity  upon  scientific  achieve- 
ment. The  third  is  Rice's  study  of  the  effect  of  different  school 
environments  upon  ability  in  spelling  and  arithmetic  ['97  and 
'02].  The  fourth  is  a  study  of  the  effect  of  changing  environment 
upon  the  choice  of  a  profession  by  scholarly  youth. 

Galton  collected  reports  from  parents  concerning  twins  who 
were  closely  similar  in  infancy  but  whose  environments  differed, 
and  twins  who  were  in  infancy  notably  unlike,  but  whose  environ- 
ments were  in  all  important  features  identical.  The  increase  of 
differences  in  the  former  case  and  of  resemblances  in  the  latter 
gives  a  measure  of  the  influence  of  the  environment.  The  per- 
sistence of  similarities  in  the  former  case  and  of  differences  in  the 
latter  gives  a  measure  of  the  influence  of  original  nature. 

This  evidence  in  the  first  case  consists  of  illustrations  of  iden- 
tical mental  habits,  tastes,  associations  of  ideas  and  suscepti- 
bilities to  mental  diseases.  The  cases  of  unlikeness  seem  to  him 
to  be  due  to  such  alterations  in  the  amount  of  energy  as  could  be 
caused  by  illness  or  lowered  nutrition  rather  than  to  fundamental 
qualities  of  mind. 

The  evidence  in  the  case  of  the  twenty  pairs  in  the  second 
group  shows  no  exceptions  to  the  rule  that  no  weakening  of 
inborn  differences  by  similarities  of  nurture  is  observable.  The 
following  are  representative  parental  observations: — 

1,  One  parent  says: — "They  have  had  exactly  the  same  nur- 
ture from  their  birth  up  to  the  present  time;  they  are  both  per- 
fectly healthy  and  strong,  yet  they  are  otherwise  as  dissimilar  as 
two  boys  could  be,  physically,  mentally,  and  in  their  emotional 
nature." 

2.  "  I  can  answer  most  decidedly  that  the  twins  have  been 
perfectly  dissimilar  in  character,  habits,  and  likeness  from  the 
moment  of  their  birth  to  the  present  time,  though  they  were 
nursed  by  the  same  woman,  went  to  school  together,  and  were 
never  separated  till  the  age  of  fifteen." 


I20  Educational  Psychology 

3.  "  They  have  never  been  separated,  never  the  least  differently 
treated  in  food,  clothing,  or  education ;  both  teethed  at  the  same 
time,  both  had  measles,  whooping-cough,  and  scarlatina  at  the 
same  time,  and  neither  had  any  other  serious  illness.  Both  are 
and  have  been  exceedingly  healthy  and  have  good  abilities,  yet 
they  differ  as  much  from  each  other  in  mental  cast  as  any  of  my 
family  differ  from  another." 

4.  "  Very  dissimilar  in  body  and  mind ;  the  one  is  quite  retir- 
ing and  slow  but  sure ;  good-tempered,  but  disposed  to  be  sulky 
when  provoked ; — the  other  is  quick,  vivacious,  forward,  acquiring 
easily  and  forgetting  soon ;  quick-tempered  and  choleric,  but 
quickly  forgetting  and  forgiving.  They  have  been  educated  to- 
gether and  never  separated." 

5.  "  They  were  never  alike  either  in  body  or  mind  and  their 
dissimilarity  increases  daily.  The  external  influences  have  been 
identical ;  they  have  never  been  separated." 

6.  "  The  two  sisters  are  very  different  in  abiUty  and  dispo- 
sition. The  one  is  retiring  but  firm  and  determined ;  she  has  no 
taste  for  music  or  drawing.  The  other  is  of  an  active,  excitable 
temperament ;  she  displays  an  unusual  amount  of  quickness  and 
talent,  and  is  passionately  fond  of  music  and  drawing.  From 
infancy,  they  have  been  rarely  separated  even  at  school,  and  as 
children  visiting  their  friends,  they  always  went  together." 

7.  "  They  have  been  treated  exactly  alike ;  both  were  brought 
up  by  hand ;  they  have  been  under  the  same  nurse  and  governess 
from  their  birth,  and  they  are  very  fond  of  each  other.  Their 
increasing  dissimilarity  must  be  ascribed  to  a  natural  difference 
of  mind  and  character,  as  there  has  been  nothing  in  their  treat- 
ment to  account  for  it." 

8.  "  They  are  as  different  as  possible.  [A  minute  and  unspar- 
ing analysis  of  the  characters  of  the  two  twins  is  given  by  their 
father,  most  instructive  to  read,  but  impossible  to  publish  without 
the  certainty  of  wounding  the  feelings  of  one  of  the  twins,  if 
these  pages  should  chance  to  fall  under  his  eyes.]  They  were 
brought  up  entirely  by  hand,  that  is,  on  cow's  milk,  and  treated 
by  one  nurse  in  precisely  the  same  manner." 

9.  "  The  home-training  and  influence  were  precisely  the  same, 
and  therefore  I  consider  the  dissimilarity  to  be  accounted  for 
almost  entirely  by  innate  disposition  and  by  causes  over  which  we 
have  no  control." 


The  Influence  of  the  Environment  121 

10.  "  This  case  is,  I  should  think,  somewhat  remarkable  for 
dissimilarity  in  physique  as  well  as  for  strong  contrast  in  char- 
acter. They  have  been  unlike  in  body  and  mind  throughout  their 
lives.  Both  were  reared  in  a  country  house,  and  both  were  at 
the  same  schools  till  aet.  16." 

The  two  lines  of  evidence  taken  together  justify,  in  Galton's 
opinion,  the  following  general  statements : 

'*  We  may,  therefore,  broadly  conclude  that  the  only  circum- 
stance, within  the  range  of  those  by  which  persons  of  similar 
conditions  of  life  are  affected,  that  is  capable  of  producing  a 
marked  effect  on  the  character  of  adults,  is  illness  or  some  acci- 
dent that  causes  physical  infirmity.  .  .  .  The  impression  that 
all  this  leaves  on  the  mind  is  one  of  some  wonder  whether  nurture 
can  do  anything  at  all,  beyond  giving  instruction  and  professional 
training.  There  is  no  escape  from  the  conclusion  that  nature 
prevails  enormously  over  nurture  when  the  differences  of  nurture 
do  not  exceed  what  is  commonly  to  be  found  among  persons  of 
the  same  rank  of  society  and  in  the  same  country." 

Even  in  the  hands  of  a  master,  the  collection  of  data  through 
correspondence  is  inferior  to  direct  observation  and  measure- 
ment. Galton  was  misled  to  believe  that  twins  fall  naturally  into 
two  groups,  those  much  alike,  and  those  little  alike,  in  infancy. 
They  do  not.  His  correspondents  may  have  made  careless  re- 
ports in  other  respects  also.  However,  it  will  be  remembered  that 
with  respect  to  fifty  pairs  of  twins,  objectively  measured,  the 
facts  showed  that  the  existing  differences  in  home  training  had 
very  slight  effects  upon  the  six  mental  abilities  tested. 

The  conditions  of  nurture  of  men  of  great  achievement  have 
been  studied  by  De  Candolle  ['73],  Galton  ['74],  Jacoby  ['81], 
Odin  ['95],  Elhs  ['04],  Cattell  ['06],  and  others.  Within  any 
one  nation  such  men  are  more  likely  than  chance  would  allow  to 
be  brought  up  in  thickly  settled  districts,  in  particular  in  cities, 
still  more  particularly,  in  the  case  of  men  of  science  or  letters, 
in  cities  containing  universities ;  by  parents  in  comfortable  or 
more  than  comfortable  financial  circumstances ;  and  to  have  re- 
ceived a  good  education. 

Such  facts  are  used  in  Odin,  and  by  Lester  F.  Ward  [06] 
following  him,  as  evidence  that  the  number  of  men  of  great  achieve- 
ment could  be  increased  many  times  over  if  all  men  had  in  vouth 
the  stimulus  of  an  intellectually  active  city,  freedom  from  pro- 


122 


Educational  Psychology 


ductive  labor,  and  good  school  training.  But  obviously  the  fea- 
tures of  the  successful  man's  surroundings,  enumerated  above, 
might  all  be  the  secondary  results  of  superior  parentage.  If  men 
of  high  capacity  go  to  live  in  cities,  their  sons  will  be  born  and 
reared  in  cities ;  if  men  of  scientific  and  literary  gifts  are  attracted 
to  university  cities,  such  cities  will,  on  grounds  of  heredity  alone, 
produce  future  scientific  and  literary  men.  If  men  of  high  achieve- 
ment are  born  of  men  of  over-average  achievement,  they  will  not 
be  brought  up  by  day-laborers  and  without  education  as  often 
as  chance  would  dictate.  The  parent's  achievement  leads  for- 
ward to  these  environmental  conditions  as  truly  as  the  son's 
achievement  leads  back  to  them.  So  nothing  is  proved  by  them. 
From  Table  ii   [Cattell,  '06],  one  can,  according  to  his  point  of 


TABLE  II. 

Distribution  of  867  Men  of  Science  Born  in  the  United  States. 

Birthplace.  Per 
Million 

I.-V*     VI.-X.*  Total.  i860. 

North  Atlantic  Division. 

Maine 19             10  29  46.1 

New  Hampshire 7               8  15  46.0 

Vermont 9               9  18  57.1 

Massachusetts 60             74  134  108 . 8 

Rhode  Island 4                i  5  28.6 

Connecticut 26             .14  40  86.9 

New  York 99             84  183  47 . 2 

New  Jersey 9              19  28  41.6 

Pennsylvania 32             34  66  23.7 

South  Atlantic  Division. 

Delaware o               2  2  17.8 

Maryland 12              14  26  37-8 

District  of  Columbia i                2  3  39-9 

Virginia 5               8  13 

West  Virginia i               o  i  8.8 

North  Carolina i                4  5  5.0 

South  Carolina 2               3  5  7.1 

Georgia i               2  3  2.8 

South  Central  Division. 

Kentucky 6               2  8  6.9 

Tennessee 5               i  6  5.4 

Alabama i                i  2  2.1 

*  Column  I -V.  gives  the  facts  for  men  of  the  highest  ability;    column 
VI.-X.  gives  the  facts  for  the  500  men  of  less  ability. 


The  Influence  of  the  Environment 


123 


I.-V.* 

Mississippi i 

Louisiana i 

Texas o 

North  Central  Division. 

Ohio 42 

Indiana 17 

Illinois 24 

Michigan 12 

Wisconsin 11 

Minnesota i 

Iowa 6 

Missouri 4 

North  Dakota 

South  Dakota 

Nebraska i 

Kansas 5 

Western  Division. 

Montana 

Wyoming 

Colorado o 

New  Mexico 

Arizona 

Washington 

California 

Alaska 

Hawaii 

Philippine  Islands 

Total 432 


Birthplace. 

Per 
Million 

VI.-X.* 

Total. 

i860. 

0 

I 

1-3 

0 

I 

1-4 

3 

3 

4-9 

33 

75 

32.1 

II 

28 

20.7 

18 

42 

24-5 

15 

27 

36.0 

24 

35 

45-1 

3 

4 

23.2 

14 

20 

29.6 

10 

14 

II. 8 

I 

2 

69 -3 

2 

7 

65.3 

87.2 


I 

0 

I 

86.2 

5 

6 

II 

28.9 

I 

0 

I 

435 


867 


27.6 


view,  get  evidence  that  educational  opportunity  counts  enormously 
or  that  it  counts  slightly  in  the  relative  production  of  scientific 
men  by  the  different  states  of  this  country. 

For  instance,  the  most  striking  fact  is  the  high  position  of  New 
England  and  the  low  position  of  the  southern  states.  The  advo- 
cate of  great  influence  from  opportunity  may  plausibly  say  that 
from  1870  to  1885,  the  time  when  most  of  the  men  in  question 
were  from  10  to  30  years  of  age,  life  in  New  England  meant 
cities,  schools,  books,  lectures,  the  personal  example  of  scholarly 
men  and  freedom  from  poverty,  whereas  life  in  the  south  meant 
the  reverse.  But  the  advocate  of  little  influence  may  retort  that 
Maine,  New  Hampshire  and  Vermont  should  not,  on  these 
grounds,  have  been  so  superior  to  Rhode  Island ;  or  Louisiana  so 


124  Educational  Psychology 

inferior  to  Texas ;  or  Missouri  so  inferior  to  Wisconsin.  He  may 
insist  that  the  chief  gift  of  Massachusetts  parents  to  their  sons  was 
the  original  nature  which  in  earHer  days  developed  commerce 
and  manufactures,  established  the  schools  and  libraries,  and  raised 
life  above  a  daily  struggle  for  physical  necessities,  while  the 
southern  planters  and  their  servants  were  content  to  leave  nature 
unimproved. 

Such  a  conflict  of  opinion  is  found  between  Professor  Cattell, 
who  gathered  the  data  of  Table  ii,  and  Professor  Woods.  Some 
of  the  comments  of  the  former  are : — ''  The  inequality  in  the 
production  of  scientific  men  in  different  parts  of  the  country 
seems  to  be  a  forcible  argument  against  the  view  of  Dr.  Galton 
and  Professor  Pearson  that  scientific  performance  is  almost  ex- 
clusively due  to  heredity.  It  is  unlikely  that  there  are  such 
differences  in  family  stocks  as  would  lead  one  part  of  the  country 
to  produce  a  hundred  times  as  many  scientific  men  as  other  parts. 
The  negroes  may  have  a  racial  disqualification,  but  even  this 
is  not  proved.  The  main  factors  in  producing  scientific  and 
other  forms  of  intellectual  performance  seem  to  be  density 
of  population,  wealth,  opportunity,  institutions  and  social 
traditions  and  ideals.  All  these  may  be  ultimately  due  to  race, 
but,  given  the  existing  race,  the  scientific  productivity  of  the 
nation  can  be  increased  in  quantity,  though  not  in  quality,  almost 
to  the  extent  that  we  wish  to  increase  it 

"  My  general  impression  is  that  certain  aptitudes,  as  for  mathe- 
matics and  music,  are  mainly  innate,  and  that  kinds  of  character 
and  degrees  of  ability  are  mainly  innate,  but  that  the  direction  of 
performance  is  mainly  due  to  circumstances,  and  that  the  environ- 
ment imposes  a  veto  on  any  performance  not  congenial  to  it." 
['06,  pp.  734-735] 

The  cities  in  which  five  or  more  of  the  thousand  men  of  science 
were  born,  are  given  in  Table  12.  [Cattell,  '06,  p.  738]  The 
author  of  the  study  is  cautious  in  estimating  the  beneficial  results 
of  city  life.  He  says  simply,  "  Of  the  866  men  native  to  the 
United  States,  224  were  born  in  the  cities  which  in  1900  had  a 
population  of  more  than  25,000.  These  places  had  in  i860  a  popu- 
lation of  about  4,500,000  as  compared  with  a  rural  population  of 
about  27,000,000.  The  urban  population  was  about  one  sixth  of 
the  rural  population  and  produced  more  than  a  quarter  of  the 
scientific  men.     The  urban  birth  rate  was  50  and  the  rural  birth 


The,  Influence  of  the  Environment  125 

rate  was  23.8.  The  superior  position  of  the  towns  is  doubtless 
due  to  a  more  favorable  environment,  but  it  may  also  be  in  part 
due  to  the  fact  that  the  parents  of  these  scientific  men  were  the 
abler  clergymen  and  others  of  their  generation  who  were  drawn 
to  the  cities.     ['06,  pp.  738-739] 

TABLE  12. 
Distribution  in  Different  Places. 

According   to  Birthplace  Per 

Million 

I  -V  VI. -X.  Total.  i860. 

New  York,  N.  Y 33  25  58  71.2 

Boston,  Mass 24  19  43  241 . 8 

Philadelphia,  Pa 12  16  28  49.5 

Baltimore,  Md 9  11  20  94.  i 

Cincinnati,  0 6  6  12  74 . 5 

Brooklyn,  N.  Y 3  8  11  39.4 

Chicago,  Ills • 5  3  8  73.2 

Buffalo,  N.  Y 3  4  7  86.2 

St.  Louis,  Mo 2  5  7  43 . 5 

Cambridge,  Mass 4  2  6  230 . 2 

Cleveland,  0 4  2  6  140. 5 

Salem,  Mass i  5  6  269 . 6 

Milwaukee,  Wis i  4  5  no. 5 

Newark,  N.J 3  2  5  69 . 5 

San  Francisco,  Cal 2  3  5  88 .0 

Total 112  115  227 

With  respect  to  the  circumstances  of  education  "  it  appears 
that  those  who  attend  the  larger  universities  are  not  of  higher 
average  performance  than  others 

"There  is  no  significant  difference  in  rank  between  the  515  men 
who  attended  the  larger  institutions  and  those  who  attended 
smaller  colleges  or  none.  It  might  be  supposed  that  abler  stu- 
dents would  be  attracted  to  a  university  such  as  Harvard,  and 
that  they  would  have  greater  opportunities  there,  but  this  appears 
not  to  be  the  case.  So  far  as  it  goes,  this  favors  the  theory  that 
men  of  science  are  born  such  and  are  not  dependent  on  the  en- 
vironment for  the  quality  of  their  performance 

"  The  conditions  are  similar  in  the  case  of  the  doctor's  degree." 
['06,  pp.  740-741] 

Dr.  Rice's  study  is  quoted  at  some  length  because  it  was  the 
first  of  a  series  of  studies  of  the  actual  results  of  school  work, 


126 


Educational  Psychology 


still  few  in  number,  but  destined  to  increase  rapidly  with  increasing 
scientific  interest  in  school  administration. 

Dr.  Rice  ['97]  tested  the  spelling  ability  of  some  33,000  children 
in  twenty-one  schools  representing  a  great  var'iety  in  spirit, 
methods,  time  given  to  spelling  and  in  other  respects.  He  then 
compared  the  conditions  in  schools  where  the  pupils  did  well  in 
spelling  with  those  in  schools  where  they  did  badly.  He  notes 
first  of  all  the  slight  differences  between  schools,  only  6  out  of 
the  21  schools  being  outside  the  limits  73.3  and  77.9,  and  the 
decrease  in  variation  amongst  schools  as  we  pass  from  lower  to 
higher  grades  (see  Table  13),  facts  which  show  that  the  differ- 
ences in  spirit  or  method  that  characterize  schools  can  not  make 
much  difference  in  achievement.  Of  school  systems  where 
mechanical  methods  are  in  use  as  compared  with  more  progressive 
systems  he  says : 

"  Indeed,  in  both  the  mechanical  and  the  progressive  schools 
the  results  were  variable;  so  that  while,  in  some  instances,  the 
higher  figures  were  secured  by  the  former,  in  others  they  were 
obtained  by  the  latter ;  and  the  same  is  true  of  the  lower  figures. 
For  example.  School  B,  No.  11,  in  which  the  best  average  (79.4) 
was  obtained,  belongs  to  a  very  progressive  system ;  while  School 
A,  No.  12,  which  made  only  73.9,  belongs  to  one  of  our  most 
mechanical  systems.  And  it  is  a  peculiar  incident  that,  in  both 
these  cities,  the  results  in  the  only  other  school  examined  are 
exactly  reversed,  although  the  environment  is  about  the  same." 

He  eliminates  the  possibility  that  home  reading  or  cultured 
parents  or  English  rather  than  foreign  parentage  is  the  cause  of 
the  differences  amongst  schools  by  making  the  comparisons  of 
Table  14. 

TABLE  14.     (No.  3  of  the  original  account) 


V 

i 

m 

0      oi 

•0  i"  "* 

©•d  ,,; 

Grade. 

0 
"S 

1 

u 

i 

a 

3 

0 

d 

2| 

^   i> 

.San 

0     Pt 

2 
< 

No.  of  Chil 

Hearing  Foi 

Language 

Home. 

2 
< 

111 

it 

M 

2 
Si 
< 

■  Fourth .  . 

4 

27 

821 

64.7 

155 

65.2 

159 

64.9 

129 

62.5 

Z    (H 

Fifth.... 

4 

29 

829 

76. 

153 

77-4 

157 

76.7 

129 

74  5 

M  w  J 

H  W   1 

Sixth. . .  . 

4 

22 

778 

69.7 

IH5 

69.6 

I&5 

70.3 

119 

704 

^^ 

Seventh.. 

4 

18 

566 

78.8 

81 

82.5 

52 

81.5 

55 

76.8 

W 

[  Eighth. .  . 

4 

19 

528 

83.1 

72 

83.2 

64 

83-2 

76 

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The  Influence  of  the  Environment 


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Educational  Psychology 


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The  Influence  of  the  Environment 


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130  Educational  Psychology 

Dr.  Rice  further  tabulated  the  results  in  accordance  with  the 
methods  of  instruction  used  in  the  different  schools,  interviewing 
some  two  hundred  teachers  for  that  purpose.  He  does  not  give 
the  detailed  results,  but  assures  us  that  there  is  no  reason  to  be- 
lieve that  there  is  any  clear  choice  between  oral  and  written  spell- 
ing, writing  isolated  words  and  writing  sentences,  the  sight  or 
flash  method  and  its  absence.  Phonic  reading  does  not  make  bad 
spellers,  nor  do  written  language  work  and  wide  general  reading 
make  good  spellers.  "  In  brief,"  says  he,  "  there  is  no  direct 
relation  between  method  and  results.  .  .  .  The  results  varied 
as  much  under  the  same  as  they  did  under  different  methods  of 
instruction." 

That  the  amount  of  time  given  is  not  the  cause  of  success  in 
teaching  spelling  is  shown  by  the  facts  of  Table  13.  Schools 
giving  15  or  20  minutes  daily  to  spelling  do  as  well  as  those 
giving  40  or  50. 

After  this  admirable  array  of  facts  Dr.  Rice  jumps  rather 
hastily  to  this  speculative  conclusion :  "  The  facts  here  presented, 
in  my  opinion,  will  admit  of  only  one  conclusion,  viz.,  that  the 
results  are  not  determined  by  the  methods  employed,  but  by  the 
ability  of  those  who  use  them.  In  other  words,  the  first  place 
must  be  given  to  the  personal  equation  of  the  teacher,  while 
methods  and  devices  play  a  subordinate  part." 

This  statement  should  have  been  based  upon  a  demonstration 
of  a  high  coefficient  of  correlation  between  the  measure  of  a  class 
in  spelling  and  the  measure  of  its  teacher  in  ability,  or  of  a  great 
increase  in  variability  in  spelling  ability  as  we  pass  from  the 
children  taught  by  one  teacher  to  the  children  taught  by  10  or 
20  different  teachers.  I  calculate  that  if  the  reliabilities  of  Dr. 
Rice's  eighth  grade  averages  are  what  they  would  seem  to  be  from 
tests  made  in  eighth  grades  by  myself  and  my  students,*  the  dif- 
ferences amongst  them  are  not  much  greater  than  we  would  ex- 
pect by  the  law  of  chance  if  the  teaching  were  in  all  cases  equally 
efficient.  The  average  deviation  from  their  mean  of  the  12  eighth 
grade  classes  which  were  tested  in  the  first  half  of  the  year  is  1.9 ; 
that  of  the  13  tested  in  the  last  half  of  the  year  is  2.6;  the 
average  deviation  by  pure  chance  of  12  eighth  grade  classes  of 
40    students    each    would   be    1.9,    the   variability   of    individuals 

*These  give  a  variability  of  12.2  amongst  the  individuals  of  the  grade. 


The  Influence  of  the  Environment  131 

being  12.2.  So,  in  the  case  of  the  eighth  grades,  we  may  need  no 
cause  at  all  for  the  differences  amongst  schools  save  the  inaccur- 
acy of  the  averages  due  to  the  small  number  of  cases. 

Dr.  Rice  measured  the  arithmetical  ability  of  some  6,000  children 
in  18  different  schools  in  7  different  cities  [02].  The  results 
of  these  measurements  are  summarized  in  Table  15.  This  table 
"  gives  two  averages  for  each  grade  as  well  as  for  each  school  as 
a  whole.  Thus,  the  school  at  the  top  shows  averages  of  80.3  and 
83.5,  and  the  one  at  the  bottom,  25.2  and  31.8.  The  first  repre- 
sents the  percentage  of  answers  which  were  absolutely  correct ;  the 
second  shows  what  per  cent,  of  the  problems  were  correct  in  prin- 
ciple, i.  e.,  the  average  that  would  have  been  received  if  no  me- 
chanical errors  had  been  made.  The  difference  represents  the 
percentage  of  mechanical  errors,  which,  I  believe,  in  most  in- 
stances, makes  a  surprisingly  small  appearance." 

From  these  results  Dr.  Rice  seeks  the  causes  of  excellence  in 
arithmetical  work,  as  in  the  case  of  spelling,  by  comparing  the 
conditions  in  the  successful  schools  with  those  in  the  unsuccessful. 
He  deals  seriatim  with  ( i )  the  home  environment  of  the  pupils ; 
(2)  the  size  of  the  classes;  (3)  the  age  of  the  children;  (4)  the 
time  of  day  of  the  test;  (5)  the  time  devoted  to  arithmetic  in 
the  school;  (6)  the  amount  of  home  work  required;  (7)  the 
methods  of  teaching;  (8)  teaching  ability  as  represented  by  a 
combination  of  education,  training  and  the  personality  of  the 
teacher;  (9)  the  course  of  study;  (10)  the  superintendent's 
training  of  teachers  ;  ( 1 1 )  the  establishment  of  demands  in  regard 
to  results;  (12)  the  testing  for  results  (a)  by  teachers  alone, 
(&)  by  teachers  and  superintendents,  (c)  by  principals,  {d)  by 
principals  and  superintendents. 

He  finds  that  the  work  depends  upon  the  method  of  testing 
for  results,  that  teachers  and  pupils  do  about  what  is  demanded  of 
them,  and  that  the  best  work  appears  when  the  superintendent,  in 
connection  with  principals  of  schools,  tests  and  rates  the  work  of 
the  classes. 

The  following  are  samples  of  the  reasoning  by  which  he 
eliminates  one  after  another  of  the  possible  causes : 

Home  Environment 

"  If  the  part  that  is  played  by  the  home  environment  should 
be  as  important  as  it  is  generally  supposed  to  be,  we  should,  of 


132  Educational  Psychology 

course,  expect  to  find  that  the  schools  represented  in  the  upper 
part  of  the  table  had  been  attended  by  children  from  cultured 
homes,  while  those  in  the  lower  part  had  been  attended  by  those 
whose  home  environment  was  very  poor.  However,  if  a  line 
should  be  drawn  across  the  middle  of  the  table,  and  the  schools 
above  it  compared  with  those  below,  such  a  condition  would  not 
be  found.  Indeed,  careful  inspection  would  show  that  the  odds 
were  certainly  not  in  favor  of  the  '  aristocratic '  districts.  Of  the 
eighteen  schools,  three  in  particular  are  representative  of  the 
latter,  and  the  best  of  these  secured  the  tenth  place,  while  the 
others  ranked  eleventh  and  sixteenth,  respectively.  The  school 
that  ranked  seventh  was  distinctively  a  school  of  the  slums.  That 
is  to  say,  the  school  laboring  under  the  poorest  conditions  in 
respect  to  home  environment  obtained  a  better  standing  than  any 
one  of  the  so-called  aristocratic  schools.  The  building  which 
stands  fifth  is  representative  of  conditions  just  a  shade  better 
than  those  of  the  slums.  And  when  I  add  that,  from  the  stand- 
point of  environment,  the  schools  of  City  I.  did  not  average  a 
single  degree  better  than  those  of  Cities  VI.  and  VII.,  I  have 
said  enough  to  show  that  the  poor  results  secured  in  the  latter 
cities  can  not  be  condoned  on  the  ground  of  unfavorable  environ- 
ment. Thus,  as  in  spelling,  so  in  arithmetic,  this  mountain,  upon 
close  inspection,  dwindles  down  to  the  size  of  a  molehill." 

Size  of  Classes 

"  Equally  surprising,  if  indeed  not  more  incredible,  may  appear 
the  statement  that  no  allowance  whatever  is  to  be  made  for  the 
size  of  the  class  in  judging  the  results  of  my  test.  I  shall  not. 
enter  into  the  details  in  regard  to  this  point,  but  will  dismiss  it 
with  the  remark  that  the  number  of  pupils  per  class  was  larger 
in  the  highest  six  schools  than  it  was  in  the  schools  of  City  VI., 
and  that  the  classes  were  exceptionally  small  in  the  school  that 
stands  at  the  lower  end." 

Age  of  Pupils 

His  argument  is  here  too  lengthy  to  quote  and  is  rather  awk- 
ward, but  sufficiently  proves  that  the  differences  between  schools 
could  have  been  due  only  in  a  very  slight  degree,  if  at  all,  to  differ- 
ences in  the  ages  of  the  pupils.  The  obvious  way  to  eliminate  age 
is  to  compare  a  group  from  City  VI.  or  VII.  with  a  group  iden- 
tical in  age  and  grade  from  City  I.  or  III. 


The  Influence  of  the  Environment  133 

Time  of  Day 

This  can  not  be  the  cause  of  much  of  the  difference  found,  for 
within  any  one  city  the  time  of  day  of  the  test  makes  Httle 
difference. 

The  Time  Devoted  to  Arithmetic  in  the  School 

"  A  glance  at  the  figures  will  tell  us  at  once  that  there  is  no 
direct  relation  between  time  and  result ;  that  special  pressure 
does  not  necessarily  lead  to  success,  and,  conversely,  that  lack  of 
pressure  does  not  necessarily  mean  failure. 

"In  the  first  place,  it  is  interesting  to  note  that  the  amount  of 
time  devoted  to  arithmetic  in  the  school  that  obtained  the  lowest 
average — 25  per  cent. — was  practically  the  same  as  it  was  in  the 
one  where  the  highest  average — 80  per  cent. — was  obtained.  In 
the  former  the  regular  time  for  arithmetic  in  all  the  grades  was 
forty-five  minutes  a  day,  but  some  additional  time  was  given. 
In  the  latter  the  time  varied  in  the  different  classes,  but  averaged 
fifty-three  minutes  daily.  This  shows  an  extreme  variation  in 
results  under  the  same  appropriation  of  time. 

"Looking  again  toward  the  bottom  of  the  list,  we  find  three 
schools  with  an  average  of  36  per  cent.  In  one  of  these,  insuffi- 
cient pressure  might  be  suggested  as  a  reason  for  the  unsatisfac- 
tory results,  only  thirty  minutes  daily  having  been  devoted  to 
arithmetic.  The  second  school,  however,  gave  forty-eight,  while 
the  third  gave  seventy-five.  This  certainly  seems  to  indicate  that 
a  radical  defect  in  the  quality  of  instruction  can  not  be  offset  by 
an  increase  in  quantity. 

'Tf  we  now  turn  our  attention  from  the  three  schools  just  men- 
tioned and  direct  it  to  three  near  the  top — Schools  2,  3,  and  4, 
City  I. — we  find  the  conditions  reversed ;  for  while  the  two  schools 
that  gave  forty-five  minutes  made  averages  of  64  per  cent,  and 
67  per  cent.,  respectively,  the  school  that  gave  only  twenty-five 
minutes  succeeded  in  obtaining  an  average  of  69  per  cent.  This 
would  appear  to  indicate  that  while,  on  the  one  hand,  nothing  is 
gained  by  an  increase  of  time  where  the  instruction  in  arithmetic 
is  faulty,  on  the  other  hand,  nothing  is  lost  by  a  decrease  of  time,  to 
a  certain  point,  where  the  schools  are  on  the  right  path  in  teaching 
the  subject.  Perhaps  the  most  interesting  feature  of  the  table  is 
the  fact  that  the  school  giving  twenty-five  minutes  a  day  came 
out  within  two  of  the  top,  while  the  school  giving  seventv-five 
minutes  daily  came  out  practically  within  one  of  the  bottom." 


134  Educational  Psychology 

The  Amount  of  Home  Work  Required 

The  greatest  amount  of  home  work  was  required  in  the  lowest 
ranking  city  while  it  had  been  practically  abandoned  in  the  first 
five  schools  of  the  table. 

In  the  other  cases  the  facts  are  given  more  vaguely,  and  in  his 
presentation  of  positive  evidence  that  differences  in  supervision 
by  tests  are  the  leading  causes  of  the  differences  in  achievement 
of  the  different  schools,  Dr.  Rice  seems  to  reach  his  conclusion 
simply  from  observing  (i)  that  all  conditions  in  City  VI.  were 
favorable  save  that  examinations  were  given  only  by  the  teacher, 
(2)  that  in  City  VII.  the  examinations  were  given  by  the  teacher 
and  perfunctorily  by  the  superintendent,  while  (3)  in  City  I.  the 
superintendent,  with  the  principals,  took  pains  in  setting  the  tests. 
It  seems  probable  that  the  cause  he  alleges  is  a  real  one,  though 
even  his  own  facts  show  the  cooperation  of  other  causes.  This 
I  take  it  he  does  not  mean  to  deny. 

The  fourth  sample  of  studies  of  the  influence  of  the  environ- 
ment is  not  of  major  importance,  but  is  distinctive  in  that  its  facts 
cannot  be  accounted  for  by  any  force  other  than  the  environment. 
The  facts  are  the  changes  in  the  careers  of  scholarly  college 
graduates  from  the  class  of  1840  to  that  of  1895,  comprising  5283 
members  of  the  honorary  society,  0  B  K,  admission  to  which 
was  substantially  a  recognition  of  superior  scholarship  in  college. 

The  four  professions,  law,  medicine,  teaching  and  the  ministry, 
have,  together,  attracted  almost  exactly  the  same  proportion  of 
scholarly  men  in  each  decade.  The  per  cent  oi  ^  B  K  gradu- 
ates entering  some  one  of  these  four  professions  was  65  in  1840- 
59,  65!/^  in  1860-69,  65  in  1870-79,  and  64  in  1880-1894. 

Among  the  professions,  however,  there  have  been  marked 
changes,  as  shown  in  Table  16.  In  twenty  years  the  law  doubled 
its  attractiveness  to  scholarly  men  and  then,  in  half  that  time, 
lost  two-thirds  of  its  gain.  Medicine  was,  in  the  last  decade  of 
the  period,  becoming  more  attractive.  The  table  shows  a  very 
rapid  rise  in  the  popularity  of  teaching  from  1840  to  i860  and 
again  from  1870  to  1895.  The  years  from  '60  to  '65  show  an 
opposite  tendency.  The  law  was  then  gaining  rapidly  and  the 
ministry  was  holding  its  own.  The  most  striking  change  was 
the  decrease  in  the  proportion  of  scholarly  men  making  the  min- 
istry their  life  work.  The  decrease  would  be  even  more  marked 
if  those  who  entered  the  ministry  but  gave  up  its  regular  work 


The  Influence  of  the  Environment  135 

for  that  of  teaching  were  inckided.  The  incomplete  records  avail- 
able in  the  ^  B  iT  Catalogue  of  1900  give  only  5><  per  cent  of 
clergymen  amongst  those  graduating  from  '95-'99 ;  and  even  with 
later  additions  the  per  cent  for   1900  is  probably  under  10. 

Roughly,  it  may  be  said  that  three-fourths  of  the  scholarly 
young  men  who  entered  the  ministry  in  1850  would  have  gone  into 
teaching  or  the  law  if  they  had  happened  to  be  born  a  half  century 
later.  The  same  original  natures  choose  differently  because  the 
social  and  intellectual   environment  has  changed. 

TABLE  16. 
Percentages  of  Scholarly  Youths  Making  Their  Life  Work  That  of  : — 
Law         Medicine     Teaching     Ministry 


1840 — 1844 

14 

1 

9-4 

37-5 

1845— 1849 

10   , 

6 

II. 6 

40 

1850— 1854 

9-3 

13-7 

36.5 

1855— 1859 

10 

5  J 

16.4 

34-5 

i860— 1864 

15 

2 

5-5 

17.2 

27-5 

1865— 1869 

19 

7 

4 

139 

28.5 

1870 — 1874 

19 

8 

5-5 

16.4 

22.5 

1875— 1879 

22 

5 

4 

17.6 

22 

1880— 1884 

16 

4 

4-5 

21.4 

195 

1885— 1889 

14 

4 

7-5 

255 

16 

1890 — 1894 

19 

7 

254 

14 

The  near  future  will  doubtless  see  a  rapid  increase  in  the  num- 
ber and  improvement  in  the  quality  of  studies  of  the  environmental 
causes  of  individual  differences  in  mental  traits.  Rice's  investi- 
gation of  the  differences  due  to  different  features  of  administra- 
tion and  teaching  has  been  followed  by  similar  studies  by  Corn- 
man  ['02],  Stone  [08],  Courtis  ['09],  and  Thorndike  ['10]. 
Experts  in  education  are  becoming  experimentalists  and  quanti- 
tative thinkers  and  are  seeking  to  verify  or  refute  the  established 
beliefs  concerning  the  effects  of  educational  forces  upon  human 
nature.  Students  of  history,  government,  sociolog}',  economics, 
ethics  and  religion  are  becoming,  or  will  soon  become,  quantitative 
thinkers  concerning  the  shares  of  the  various  physical  and  social 
forces  in  making  individual  men  differ  in  politics,  crime,  wealth, 
service,  idealism,  or  whatever  trait  concerns  man's  welfare. 

But  for  the  present  the  exact  answers  to  such  questions  are 
lacking  and  all  that  can  wisely  be  offered  is  a  general  statement 
of  how  outside  forces  do  act  upon  original  natures  so  as  to  make 
them  more  alike  or  more  different  than  they  would  otherwise  be. 


136  Educational  Psychology 

The  Method  of  Action  of  Diiferences  in  Environment 

We  may  summarize  the  methods  whereby  different  environ- 
ments act  upon  intellect  and  morals  as : — 

1.  Furnishing  or  withholding  the  physiological  conditions  for 
the  brain's  growth  and  health. 

2.  Furnishing  or  withholding  adequate  stimuli  to  arouse  the 
action  of  which  the  brain  is  by  original  nature  or  previous  action 
capable. 

3.  Reinforcing  some  and  eliminating  others  of  these  activi- 
ties in  consequence  of  the  general  law  of  selection  in  mental  life.* 

According  to  this  description  we  should  look  upon  the  mental 
life  of  an  individual  as  developing  in  the  same  way  that  the 
animal  or  plant  kingdom  has  developed.  As  conditions  of  heat 
and  food-supply  have  everywhere  been  the  first  requisite  to 
and  influence  on  animal  life,  so  the  physiological  conditions  of 
the  brain's  activities  are  the  first  modifiers  of  feeling  and  action. 
As  the  stimuli  of  climate,  food,  unknown  chemical  and  electrical 
forces  and  the  rest  have  been  the  means  of  creating  variations  in 
the  germs  or  of  stimulating  to  action  the  inner  tendency  of  the 
germs  to  vary,  and  so  have  rendered  possible  the  production  of 
millions  of  different  animal  types,  so  the  sights  and  sounds  and 
smells  of  things,  the  words  and  looks  and  acts  of  men,  the  uten- 
sils and  machinery  and  buildings  of  civilization,  its  pictures  and 
music  and  books,  awaken  in  the  mind  new  mental  varieties,  new 
species  of  thoughts  and  acts.  In  a  score  of  years  from  birth  the 
human  mind,  like  the  animal  world,  originates  its  universe  of  mental 
forms.  And  as,  in  the  animal  kingdom,  many  of  these  variations 
fail  to  fit  the  conditions  of  physical  nature  and  die  after  a  genera- 
tion or  two,  so  in  any  one  of  us  many  of  the  mental  forms  pro- 
duced are  doomed  to  a  speedy  disappearance  in  consequence  of 
their  failure  to  fit  outside  events.  The  elimination  of  one  species 
by  others  in  the  animal  world  is  again  paralleled  by  the  death 
of  those  thoughts  or  acts  which  are  out  of  harmony  with  others. 
Species  of  thoughts,  like  species  of  animals,  prey  upon  one  another 
in  a  struggle  in  which  survival  is  the  victor's  reward.     Further, 

*In  all  animals  capable  of  profiting  by  training  any  act  which  in  a  given 
situation  brings  satisfaction  becomes  thereby  more  closely  associated  with 
that  situation,  so  that  when  that  situation  recurs  the  act  will  recur  also. 
An  act  that  brings  discomfort  becomes  dissociated  from  the  situation  and 
less  likely  to  recur. 


The  Influence  of  the  Environment  137 

just  as  species  of  animals  fitted  to  one  environment  perish  or 
become  transformed  when  that  environment  changes,  so  mental 
forms  fitted  to  infancy  perish  or  are  transformed  in  school  life ; 
mental  forms  fitted  to  school  life  perish  in  the  environment  of 
the  workaday  world ;  and  so  throughout  the  incessant  changes 
of  a  mind's  surroundings.  In  mental  life  resulting  pain  or  dis- 
comfort is  the  cause  of  the  extinction  of  a  species.  The  condi- 
tion of  a  man's  mind  at  any  stage  in  its  history  is  then,  like  the 
condition  of  the  animal  kingdom  at  any  stage  in  the  history  of 
the  world,  the  result  not  only  of  the  new  varieties  that  have  ap- 
peared, but  also  of  a  natural  selection  working  upon  them.  The 
tale  of  a  human  mind's  progress  is  the  tale  of  the  extinction  of 
its  failures.  Possibility  of  existence,  stimuli  to  variations,  selec- 
tion by  elimination:  these  words  that  describe  the  action  of  the 
environment  on  animal  life  are  equally  competent  to  tell  the 
record  of  a  human  life. 

The  influence  of  any  environmental  agency,  physical  or  social, 
varies  with  its  avoidability.  Oligarchies  lose  in  influence  if  there 
is  a  democracy  to  which  men  may  emigrate.  Customs  do  not 
make  men  so  infallibly  if  there  is  a  radical  party,  however  small, 
which  offers  an  alternative  mode  of  life.  Music's  charms  to 
soothe  obviously  are  not  so  universal  if  men  can  close  their  ears. 
A  creed  loses  authority  as  soon  as  one  disbeliever  seeks  converts. 
Social  environments,  institutions,  beliefs  and  modes  of  behavior 
are  nearly  omnipotent  when  undisputed ;  for  to  be  the  first  man  to 
revolt  means  either  that  one  is  a  mere  eccentric  and  so  sure  to  i 
be  a  failure,  or  that  one  is  a  genius  and  so  very  rare.  ^But  once 
a  revolt  is  started  and  advertised,  it  may  much  more  easily  attract 
those  whose  original  natures  it  fits.  And  they  may  be  the  more 
attracted  by  it  for  having  been  exposed  to  the  opposite  force.  So 
a  given  environmental  force  may  even  act  as  a  stimulus  toward 
just  the  opinions,  interests  or  acts  that  it  is  designed  to  thwart. 

There  are  many  differences  in  thought  and  conduct  which  are 
nearly  equally  tolerated  by  all  original  natures.  To  wear  a  hat 
or  not  to  wear  a  hat,  to  express  requests  and  opinions  in  English 
or  to  express  them  in  German,  to  learn  astrolog\^  or  to  learn  the 
Ptolemaic  astronomy  or  to  learn  the  Copernican  astronomy — to 
all  original  natures  these  are  nearly  indifferent  issues.  Which  is 
done  depends  almost  exclusively  on  environment.  In  general  this 
is  true  of  all  ,the  '  whats  '  of  knowledge  and  technique.     How 


138  Educational  Psychology 

many  and  hoiv  hard  things  a  man  can  learn  or  do  are  largely  de- 
cided by  original  nature,  but,  within  these  limits,  what  he  learns 
or  does  is  largely  a  matter  of  what  he  is  stimulated  to  do  and 
rewarded  for  doing.  On  the  other  hand,  there  are  many  features 
of  original  nature  each  of  which  acts  to  produce  nearly  the  same 
efifect  in  spite  of  such  differences  in  outside  forces  as  different 
men  can  meet  in  modern  civilized  countries.  In  such  countries 
it  seems  possible  for  any  one  to  be  a  poet,  or  to  be  a  political  leader, 
or  to  be  a  money-maker,  if  his  nature  so  orders.  Original  nature 
in  general  is  not  irrepressible,  and  no  form  of  it  is  absolutely 
irrepressible ;  but  some  forms  of  original  nature  seem  to  be  nearly 
irrepressible  by  any  of  the  environments  a  man  in  this  country  is 
likely  to  have. 

The  Relative  Importance  of  Original  Nature  and  Environment 

It  is  impossible  at  present  to  estimate  with  security  the  relative 
shares  of  original  nature,  due  to  sex,  race,  ancestry  and  accidental 
variation,  and  of  the  environment,  physical  and  social,  in  causing 
the  differences  found  in  men.  One  can  only  learn  the  facts,  in- 
terpret them  with  as  little  bias  as  possible,  and  try  to  secure  more 
facts.  This  interpretation  is  left  to  the  student,  but  with  certain 
cautions  in  addition  to  or  in  amplification  of  those  already 
explained. 

Many  of  the  false  inferences  about  nature  versus  nurture  are 
due  to  neglect  of  the  obvious  facts : — that  if  the  environments  are 
alike  with  respect  to  a  trait,  the  differences  in  respect  to  it  are 
due  entirely  to  original  nature ;  that  if  the  original  natures  are 
alike  with  respect  to  a  trait,  the  differences  in  respect  to  it  are 
due  entirely  to  differences  in  training ;  and  that  the  problem  of 
relative  shares,  where  both  are  effective,  includes  all  the  separate 
problems  of  each  kind  of  environment  acting  with  each  kind  of 
nature.    Any  one  estimate  for  all  cases  would  be  absurd. 

Many  disagreements  spring  from  a  confusion  of  what  may  be 
called  absolute  achievement  with  what  may  be  called  relative 
achievement.  A  man  may  move  up  a  long  distance  from  zero 
and  nevertheless  be  lower  down  than  before  in  comparison  with 
other  men :  absolute  gain  may  be  relative  loss.  One  thinker  may 
attribute  differences  in  achievement  almost  wholly  to  nurture 
while  another  holds  nature  to  be  nearly  supreme,  though  both 


The  Influence  of  the  Environment  139 

thinkers  possess  just  the  same  data,  if  the  former  is  thinking  of 
absolute  and  the  latter  of  relative  achievement.  The  commonest 
error  resulting  is  that  of  concluding  from  the  importance  of  sex 
and  ancestral  heredity  that  education  and  social  control  in  general 
are  futile.  On  the  contrary,  as  I  have  elsewhere  said,  such  studies 
as  those  of  chapters  III,  IV,  and  V  merely  prove  the  existence  of, 
and  measure  certain  determinants  of,  human  intellect  and  charac- 
ter and  demonstrate  that  the  influences  of  the  environment  are 
differential,  the  product  varying  not  only  in  accord  with  the  en- 
vironmental force  itself  but  also  in  accord  with  the  original  nature 
upon  which  it  operates.  We  may  even  expect  that  education 
will  be  doubly  effective,  once  society  recognizes  the  advantages 
given  to  some  and  denied  to  others  by  heredity.  That  men  have 
different  amounts  of  capacity  does  not  imply  any  the  less  advan- 
tage from  or  need  of  wise  investment.  If  it  be  true,  for  example, 
that  the  negro  is  by  nature  unintellectual  and  joyous,  this  does  not 
imply  that  he  may  not  be  made  more  intelligent  by  wiser  training 
or  misanthropic  and  ugly-tempered  by  the  treatment  he  now 
receives.  It  does  mean  that  we  should  be  stupid  to  expect  the 
same  results  from  him  that  we  should  from  an  especially  intel- 
lectual race  like  the  Jews,  and  that  he  will  stand  with  equanimity 
a  degree  of  disdain  which  a  Celt  would  requite  with  dynamite  and 
arson. 

To  the  real  work  of  man  for  man, — the  increase  of  achievement 
through  the  improvement  of  the  environment, — the  influence  of 
heredity  offers  no  barrier.  But  to  the  popular  demands  from  edu- 
cation and  social  reforms  it  does.  For  the  common  man  does  not 
much  appreciate  absolute  happiness  or  absolute  betterment.  He 
does  not  rejoice  that  he  and  his  children  are  healthier,  happier  and 
more  supplied  with  noble  pleasures  than  were  his  ancestors  of  a 
thousand  years  ago.  His  complaint  is  that  he  is  not  so  well  off 
as  some  of  those  about  him ;  his  pride  is  that  he  is  above  the  com- 
mon herd.  The  common  man  demands  relative  superiority, — to 
be  above  those  of  his  own  time  and  locality.  If  his  son  leads 
the  community,  he  does  not  mind  his  real  stupidity ;  to  be  the 
handsomest  girl  in  the  county  is  beauty  enough.  Social  discon- 
tent comes  from  the  knowledge  or  fancy  that  one  is  below  others 
in  welfare.  The  effort  of  children  in  school,  of  men  in  labor  and 
of  women  in  the  home  is,  except  as  guided  by  the  wise  instincts 
of  nature  or  more  rarely  by  the  wisdom  of  abstract  thought,  to 


140  Educational  Psychology 

rise  above  some  one  who  seems  higher.  Thus  the  prizes  which 
most  men  really  seek  are  after  all  in  large  measure  given  or 
withheld  by  original  nature.  In  the  actual  race  of  life,  which  is 
not  to  get  ahead,  but  to  get  ahead  of  somebody,  the  chief  determin- 
ing factor  is  heredity. 

But  the  prizes  which  education  ought  to  seek  are  all  within 
its  power.  The  results  for  which  a  rational  mankind  would  strive 
are  determined  largely  by  mankind  itself.  For  the  common  good 
it  is  indifferent  zvho  is  at  the  top, — ivhich  men  are  achieving 
most.  The  important  thing  for  the  common  good,  for  all  men, 
is  that  the  top  should  be  high — that  much  should  be  achieved. 
To  the  absolute  welfare  of  all  men  together  education  is  the 
great  contributor. 

Another  caution  is  not  to  make  false  inferences  about  moral 
responsibility  from  the  fact  that  individual  differences  are  in  large 
measure  due  to  nature ;  nor  to  use  such  false  inferences  to  discour- 
age acceptance  of  evidence  in  support  of  this  fact. 

It  is  from  time  to  time  complained  that  a  doctrine  which  re- 
fers mental  traits  largely  to  original  make-up,  and  consequently  to 
ancestry,  discourages  the  ambitions  of  the  well-intentioned  and 
relieves  the  world's  failures  from  merited  contempt.  But  every 
one  is  agreed  that  a  man's  free  will  works  only  within  limits,  and 
it  will  not  much  matter  for  our  practical  attitude  whether  those 
limits  are  somewhat  contracted.  If  the  question  is  between  orig- 
inal nature  and  the  circumstances  of  nurture  it  is  rather  more 
encouraging  to  believe  that  success  will  depend  on  inherent  quali- 
ties than  to  refer  it  entirely  to  advantages  possessed  during  life, 
and  contempt  is  merited  more  by  him  who  has  failed  through 
being  the  inferior  person  than  by  the  one  who  has  failed  simply 
from  bad  luck.  Whether  or  not  it  is  merited  in  either  of  the 
two  cases  we  shall  decide  in  view  of  our  general  notions  about 
merit  and  blame,  not  of  our  psychological  theories  of  the  causes 
of  conduct. 

On  the  whole  it  seems  certain  that  prevalent  opinions  much 
exaggerate  the  influence  of  differences  in  circumstances  and  train- 
ing in  producing  the  intellectual  and  moral  differences  found  in 
men  of  the  same  nation  and  epoch.  Certain  natures  seem  to  have 
been  made  by  certain  environments  when  really  the  nature  already 
made  selected  that  environment.     Certain  environments  seem  to 


The  Influence  of  the  Environment  141 

eliminate  certain  traits  from  an  individual  when  really  they  merely 
expel  the  individual  in  toto. 

Thinkers  about  the  organized  educational  work  of  church, 
library  and  school  need  especially  to  remember  three  facts. 

First. — For  the  more  primitive  and  fundamental  traits  in  hu- 
man nature  such  as  energy,  capability,  persistence,  leadership, 
sympathy  and  nobility  the  whole  world  affords  the  stimulus,  a 
stimulus  that  is  present  well-nigh  everywhere.  If  a  man's  origi- 
nal nature  will  not  respond  to  the  need  of  these  qualities  and  the 
rewards  always  ready  for  them  it  is  vain  to  expect  much  from 
the  paltry  exercises  of  the  schoolroom. 

Second. — The  channels  in  which  human  energy  shall  proceed, 
the  specific  intellectual  and  moral  activities  that  shall  profit  by 
human  capacities,  are  less  determined  by  inborn  traits.  The 
schools  should  invest  in  profitable  enterprises  the  capital  nature 
provides.  We  can  not  create  intellect,  but  we  can  prevent  such  a 
lamentable  waste  of  it  as  was  caused  by  scholasticism.  We  can 
not  double  the  fund  of  human  sympathy,  but  we  can  keep  it 
clear  of  sentimental  charity. 

Third. — Morality  is  more  susceptible  than  intellect  to  environ- 
mental influence.  Moral  traits  are  more  often  matters  of  the 
direction  of  capacities  and  the  creation  of  desires  and  aversions. 
Over  them  then  education  has  greater  sway,  though  school  educn- 
tion,  because  of  the  peculiar  narrowness  of  the  life  of  the  school- 
room, has  so  far  done  little  for  any  save  the  semi-intellectual 
virtues. 

The  one  thing  that  educational  theorists  of  to-day  seem  to 
place  as  the  foremost  duty  of  the  schools — the  development  of 
powers  and  capacities — is  the  one  thing  that  the  schools  or  any 
other  educational  forces  can  do  least.  The  one  thing  that  they  can 
do  best  is  to  establish  those  particular  connections  with  ideas  which 
we  call  knowledge  and  those  particular  connections  with  acts 
which  we  call  habits. 


CHAPTER  VIII 

The  Nature  and  Amount  of  Individual  Differences  in 
Single  Traits 

For  the  purpose  of  the  following  discussion,  let  a  '  single  trait ' 
be  defined  as  one  whose  varying  conditions  in  men  can  be  meas- 
ured on  one  scale.  A  combmation  of  traits  requires  two  or  more 
scales.  For  example,  in  so  far  as  the  difference  between  John 
and  James  in  reaction  time  to  sound  can  be  measured  as  so  many 
thousandths  of  a  second  on  one  scale,  reaction  time  to  sound  is  a 
single  trait.  The  difference  between  John  and  James  in  tempera- 
ment, on  the  contrary,  can  be  stated  only  in  terms  of  several 

scales,  such  as  quick slow,  intense superficial, 

broad narrow,  and  the  like.  So  temperament  is  to  be  re- 
garded as  a  combination  of  traits. 

Individuals  may  be  compared  with  respect  to  one  trait  at  a 
time,  or  with  respect  to  certain  combinations  of  traits.  We  natur- 
ally take  up  first  the  simpler  case. 

The  most  desirable  description  of  the  differences  between  in- 
dividuals in  a  mental  trait  would  be  to  give  the  facts  for  all  hu- 
man beings,*  then  for  all  of  each  sex,*  then  for  all  of  each  race 
and  of  one  sex,*  and  so  on  for  each  stock,  degree  of  maturity,  and 
kind  of  training.  That  is,  the  condition  of  the  individuals  in  each 
of  a  great  many  groups,  each  defined  by  sex,  ancestry,  age  and 
training,  would  be  described.  By  combining  these  one  could  de- 
scribe the  condition  of  the  individuals  in  groups  defined  by  sex 
and  age  alone,  or  race  and  age  alone,  or  race,  age  and  training 
alone,  and  the  like. 

For  practical  reasons,  however,  the  individuals  whose  differ- 
ences one  from  another  have  been  measured  often  form  groups 
of  a  somewhat  adventitious  character.  For  example,  the  indi- 
vidual differences  between  one  student  and  another  in  university 
classes  in  psychology  have  been  measured,  because  such  classes 

*That  is  for  a  random  sampling  of  them. 

(142) 


Individual  Differences  in  Single  Traits  143 

are  at  the  psychologist's  service.  So  also  "  college  freshmen  ", 
or  "  children  of  a  certain  school  grade  ",  or  "  those  who  are  will- 
ing to  reply  to  a  series  of  questions  sent  out  by  mail  "  are  groups 
determined  by  convenience  rather  than  by  significance. 

The  group  is  often  deliberately  narrowed,  as  when  the  indi- 
viduals are  all  insane,  or  all  intellectually  deficient,  or  all  morally 
delinquent,  or  all  men  of  science. 

Furthermore,  many  of  the  facts  concerning  individual  dififer- 
ences  came  as  by-products  of  investigations  of  general  mental 
laws  or  of  group  differences.  For  example,  the  early  investigators 
of  the  least  noticeable  difference,  of  the  time  required  for  a  simple 
reaction  or  for  a  reaction  with  discrimination,  of  the  range  of 
consciousness  and  the  like,  often  considered  the  divergences  of 
single  men  from  the  average  of  all  men  as  "  errors  "  due  to  chance 
conditions.  These  investigators  took  no  interest  in  these  individ- 
ual divergences  save  as  annoying  hindrances  to  the  exact  formu- 
lation of  constant  laws  of  mental  life.  So  also  students  primarily 
interested  in  the  differences  of  man  from  woman  have,  without 
desire,  got  results  concerning  the  differences  of  one  man  from 
another. 

Finally  the  experiments  made  for  us  by  the  general  conditions 
of  life  often  provide  data  concerning  the  differences  of  individuals 
within  a  group  constituted  by  some  very  complex  circumstances. 
The  differences  of  teachers  in  respect  to  salary,  of  college  gradu- 
ates in  respect  to  general  achievement  in  life,  or  of  criminals  in 
respect  to  the  number  and  nature  of  their  convictions  by  courts 
of  law  are  samples. 

As  a  result,  there  does  not  exist  any  study  of  the  differences 
of  a  random  sampling  of  all  human  beings  in  a  single  mental 
trait ;  or  of  a  random  sampling  of  individuals  of  the  same  sex ;  or 
of  individuals  of  the  same  sex  and  age.  There  are,  however,  stud- 
ies of  the  differences  of  a  random  sampling  of  individuals  of  the 
same  sex  and  approximately  the  same  age  and  race.  The  boys 
12  years  o  months  to  13  years  o  months  old  found  in  the  schools 
of  a  German  or  English  town  would  form  such  a  group,  and  such 
boys  have  been  measured  with  respect  to  certain  mental  traits. 
There  are  also  studies  of  individuals  of  the  same  sex  and  of  nearly 
the  same  age,  race,  and  training  (in  certain  particulars).  The 
children  just  mentioned,  if  limited  to  a  given  grade  or  standard 
in  school,  would  be  thus  nearly  alike  in  respect  to  school  training. 


144 


Educational  Psychology 


In  spite  of  the  difificulties  of  interpretation  that  arise  from  the 
mixture  of  unknown  degrees  of  age,  race  and  training,  four  gen- 
eral facts  about  individual  variations  in  traits  taken  one  at  a 
time  seem  highly  probable.  ( i )  The  variations  are,  in  general, 
greater  in  acquired  than  in  original  traits.  (2)  They  are,  in 
general,  greater  in  traits  peculiar  to  man  than  in  traits  character- 
istic of  all  mammals.  (3)  The  variations  are  usually,  perhaps  al- 
ways, continuous.  One  grade  or  degree  or  amount  is  not  sepa- 
rated from  the  next  as  ten  men  is  separated  from  eleven  men,  but 

TABLE  17. 

The  Abilities  of  37  Adult  Women  Students  in  Adding,  after  One 
Hour's  Special  Practice.  Time  Required  (in  Seconds)  to  Add  48 
Single  Columns  Each  of  10  Figures  Taken  at  Random  from  the 
Series  2-9.  50  Per  Cent  of  the  Time  for  One  Column  Was  Added 
FOR  Each  Wrong  Sum. 


a 

c3 

nJ 

CS 

cS 

CS 

3 

3 

S 

3 

3 

3 

>. 

•  f-4 

12 
> 

>. 

"2 

^ 

13 

c 

< 

C 
1— ( 

Xi 

< 

0 
1— ( 

< 

a 
»— 1 

XI 

< 

a 
•—1 

X 
< 

T3 

C 

H- ( 

x 
< 

a 

240 

h 

390 

0 

465 

V 

508 

C 

669 

T 

845 

b 

242 

1 

428 

P 

482 

w 

535 

D 

719 

K 

896 

c 

249 

1 

433 

q 

488 

X 

545 

K 

729 

d 

267 

k 

437 

r 

489 

y 

550 

F 

741 

e 

272 

1 

459 

s 

499 

z 

572 

G 

7(^3 

1 

290 

m 

463 

t 

504 

A 

628 

H 

772 

g 

315 

n 

464 

u 

506 

B 

642 

1 

811 

TABLE  i8. 

The  Abilities  of  37  Adult  Women  Students  in  Drawing  Lines  to  Equal 

100  MM.  Lines:   Average  Error  (in  mm.)  from  the  Standard. 


« 

03 

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re 

3 

3 

3 

3 

3 

3 

12 

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"2 

>> 

3 

>-. 

12 

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'> 

-^ 

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t^ 

1— 1 

X 

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3 

1— 1 

X 

<; 

^3 

n 

X 

< 

•a 

x 
< 

c 
1— ( 

x 

< 

•d 
c 

X 

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I 

9 

8 

2.0 

15 

2.8 

22 

3-4 

29 

4-9 

36 

91 

2 

1-3 

9 

2.  2 

lb 

2 

9 

23 

3 

7 

30 

5 

2 

37 

10.2 

3 

1-5 

10 

2.3 

17 

2 

9 

24 

3 

8 

31 

5 

5 

4 

1.6 

II 

2.4 

18 

3 

I 

25 

3 

9 

32 

5 

9 

5 

1.8 

12 

2.6 

19 

3 

1 

26 

4 

2 

33 

6 

0 

6 

1.8 

13 

2.7 

20 

3 

3 

27 

4 

4 

34 

6 

7 

7 

1-9 

14 

2.7 

21 

3 

4 

28 

4 

6 

35 

7 

3 

Individual  Differences  in  Single  Traits  145 

as  ten  pounds  is  separated  from  eleven  pounds.     (4)  The  varia- 
tions usually  cluster  around  one  central  tendency  or  "  type." 

Sample  Surfaces  of  Frequency  of  Single  Traits 

As  a  preliminary  to  the  discussion  of  these  Laws  of  Mental 
Variations  I  present  in  Tables  17  and  18  and  Fig.  26  samples  of 
measurements  of  groups  of  individuals  in  traits  taken  singly. 

From  these  tables  one  can  calculate  the  amounts  of  difference 
existing  and  the  relative  frequency  of  each.  For  example,  in 
Table  17  it  appears  that  the  two  most  unlike  individual?  of  37 
chosen  at  random  from  women  students  of  education  differed 
by  656  seconds  (896-240)  in  adding  48  examples,  or  by  13^ 
seconds  per  example.  Differences  of  12  seconds  or  over  per  ex- 
ample (576  seconds  or  over  for  48  examples)  occurred  11  times 

111     Ml      I  III  ii|ii  m  III    I        II  II  III 

nh  m  m 


J_J 


V        w        IS        Q        ss        w        n)        IS        '10, 

Fig.  26.  (Upper  Diagram).  The  ability  of  each  of  ^y  women  in  adding. 
The  scale  gives  the  time  in  seconds  required  to  add  48  single  columns,  each 
of  ID  figures,  50  per  cent  of  the  time  for  one  column  being  added  for  each 
wrong  sum.    Each  vertical  line  represents  one  individual. 

Fig.  26.  (Lower  Diagram).  The  ability  of  each  of  37  women  in  draw- 
ing lines  to  equal  a  100  mm.  line.  The  scale  gives  the  average  deviation  in 
millimeters  from  the  standard.    Each  vertical  line  represents  one  individual. 

(between  each  of  individuals  a,  b,  c,  and  d  and  each  of  individuals 
J  and  K ;  also  between  each  of  individuals  e,  f  and  g  and  indi- 
vidual K)  ;  etc.,  etc.  The  median  of  all  the  individual  differences 
will  be  found,  by  any  patient  reader  who  cares  to  compute  it,  to 
be  about  33^  seconds  per  example.  The  median  of  the  deviations 
of  the  37  individuals  each  from  11  seconds  per  example,  which  is 
the  central  tendency  of  adult  women  students  of  education  in  this 
trait,  is  2.2  seconds  per  example. 


146  Educational  Psychology 

The  Amounts  of  Difference  in  Different  Traits 

Any  such  measurements  of  the  frequencies  of  different  degrees 
of  difference  between  one  individual  and  another  or  between  indi- 
viduals and  some  central  tendency  or  type,  are  not,  however,  read- 
ily commensurate  except  within  the  same  trait.  To  the  question, 
"  Do  these  women  differ  more  in  ability  to  add  than  in  ability 
to  accurately  equal  a  length  of  100  mm?,"  the  answer  is: — The 
range  of  difference  is  13^  seconds  in  one  case,  (5  to  i8f),  9.1 
millimeters  in  the  other;  the  median  difference  is  3.5  seconds 
(approx.)  in  one  case  and  1.8  millimeters  (approx.)  in  the  other; 
the  median  deviation  from  the  central  tendency  is  2.2  seconds 
in  one  case  and  1.2  millimeters  in  the  other. 

Now  in  common  speech,  and  in  books  on  psychology  and  edu- 
cation as  well,  the  differences  between  two  individuals  in  two  or 
more  mental  traits  are  compared.  Such  statements  as,  "  John 
differs  little  from  James  in  memory,  and  much  in  judgment,"  or 
"  Men  are  much  more  alike  in  sense  powers  than  in  imagery,"  are 
made.  If  they  are  justifiable,  the  differences  in  different  traits  must 
somehow  have  been  made  commensurate. 

In  particular,  my  statement  concerning  the  variations  in  original 
versus  acquired  traits,  or  in  mammalian  versus  distinctively  hu- 
man traits,  must  depend  upon  some  means  of  comparing  the  mag- 
nitudes of  variations  in  different  traits. 

In  comparing  the  tallest  and  shortest  of  100  adult  men,  we 
can  say,  not  only  that  they  differ  by,  say,  20  inches,  but  also  (sup- 
posing them  to  be  76  and  56  inches)  that  the  tallest  is  one  and  five 
fourteenths  times  as  tall.  In  comparing  the  wealth  of  the  men 
we  can  say  not  only  that  one  has  $10,000  more,  but  also  that  (sup- 
posing them  to  possess  $1,000  and  $11,000)  he  is  eleven  times  as 
rich.  In  a  certain  real  and  useful,  tho  limited,  sense,  it  can 
be  said  that  adult  men  differ  more  in  wealth  than  they  do  in 
weight,  and  more  in  weight  than  they  do  in  stature.  The  ratio 
of  the  difference  of  one  man  from  absolute  zero,  or  just  not  any 
amount  of  the  thing  in  question,  to  the  difference  of  another  man 
from  the  same  zero  or  just-not-ness  is  in  a  sense  commensurate  with 
a  similar  ratio  in  the  case  of  another  thing.  Nothingness  is  taken 
to  be  the  standard  and  *  just  not  any '  of  one  thing  is  treated  as 
equivalent  to  '  just  not  any '  of  another  thing. 

If  one  wished  to  use  the  test  in  addition  to  place  a  person  on  a 


Individual  Differences  in  Single  Traits  147 

scale  for  "  ability  in  addition  "  one  would  find  no  such  clear  and 
sure  way  to  make  the  judgment  of  "  times  as  far  from  o 
ability."  It  would  be  very  hard  to  define  "  ability  to  add  which 
is  just  barely  not  no  ability  to  add  "  in  terms  of  any  test's  score. 
It  would  be  still  harder,  if  not  impossible,  to  define  it  in  terms  of 
a  score  in  this  test.  Should  it  be  100  sec.  per  example,  or  1000, 
or  10,000,  or  100,000,  or  infinity? 

If  one  wished  to  use  the  test  in  drawing  lines  to  place  a  person 
on  a  scale  for  ability  to  notice  differences  he  would  have  not 
quite  so  hard  a  task.  For  there  would  be  some  reason  for  taking, 
as  o  ability,  a  divergence  of  100  mm., — that  is,  failure  to  distin- 
guish from  the  standard  a  line  of  zero  length. 

There  is  great  absurdity  in  common  opinions  of  what  "  just  not 
o  "  is  in  the  case  of  a  mental  trait  and  of  what  the  relative  dififer- 
ences  between  this  and  that  manifestation  of  the  trait  and  o  are. 
Even  gifted  and  well  trained  thinkers  wnll  assert,  some  that  the 
best  handwriting  is  only  one  and  a  half  times  as  "  good  "  as  a 
nearly  illegible  scrawl,  and  some  that  it  is  eight  or  ten  times  as 
good.  They  will  declare,  some  that  the  average  man  knows  twice 
as  much  as  the  average  dog,  and  some  that  he  knows  a  thousand 
times  as  much.  Some  of  them  will  assert,  on  finding  that  one 
boy  spells  48  words  correctly  out  of  a  list  of  50  and  another  6, 
that  the  former  was  thereby  proved  to  be  eight  times  as  good  a 
speller.  Even  if  we  should  all  study  somewhat  exhaustively  the 
logic  of  the  "  times  "  judgment  in  mental  traits,  there  would  still 
be  fairly  wide  disagreements  concerning,  say,  how  many  times 
as  much  curiosity  the  most  curious  man  had  than  the  average  man 
or  than  the  least  curious  man ;  or  concerning  how  many  times  as 
much  mathematical  knowledge  the  most  learned  mathematician  had 
than  the  stupidest  idiot. 

But  by  any  rational  and  just  decision  as  to  what  '  o  '  or  '  just 
not  anything '  was  for  each  mental  ability,  we  should  find  abun- 
dant evidence  of  the  truth  of  the  two  laws — that  individual  differ- 
ences in  single  traits  are  greater  in  acquired  than  in  original  abili- 
ties ;  and  that  they  are  greater  in  abilities  peculiar  to  man  than  in 
abilities  possessed  by  mammals  in  general. 

For  example,  suppose  that  we  regard  as  absolute  zeros,  the 
following:  just  not  any  A's  marked  in  a  minute,  just  not  any 
sums  correctly  given  in  a  minute,  just  not  any  dots  placed  in  a 
series  of  squares,  and  the  like,  using  as  the  measure  in  every  case 


148  Educational  Psychology 

the  amount  done  of  some  task,  some  amount  of  which  nearly  all 
adult  Americans  can  do.  The  '  times  as  much  '  then  comes  out 
greater  for  thought  than  for  movement,  greater  for  memory  of  a 
passage  than  for  memory  of  unrelated  words  or  numbers,  greater 
for  responding  to  the  meanings  of  words  than  for  responding  to 
the  differences  of  colors,  greater  for  marking  words  containing 
both  a  and  t  than  for  marking  A's  amongst  other  letters,  greater 
in  solving  problems  in  arithmetic,  mechanical  difficulties,  or  geo- 
metrical puzzles  than  in  sorting  out  colors. 
f^'"  For  the  reasons  stated  at  the  beginning  of  this  chapter  a  survey 
of  the  data  bearing  on  the  comparative  variability  of  man  in  dif- 
ferent traits  would  not  be  desirable,  even  apart  from  the  difficulty 
of  choosing  zero  points.  Moreover,  the  truth  of  the  statement  that 
as  a  rule  individuals  differ  more  in  acquired  than  in  original  traits 
hardly  needs  statistical  proof.  The  range  of  variations  or  the 
average  individual  difference  is  obviously  greater  in  the  acquired 
perceptions  of  words,  music,  geometrical  forms  and  the  like  than 
in  the  original  sensitivities  to  colors,  sounds  or  distances ;  in  the 
acquired  movements  of  writing,  sewing,  singing  and  the  like  than 
in  the  original  reflexes  and  instincts  of  winking,  swallowing, 
clasping,  running  or  striking ;  in  knowledge,  which  is  largely  ac- 
quired, than  in  movement,  which  is  to  a  considerable  extent  orig- 
inal ;  in  the  interests  in  literature,  science  or  politics  than  in  the 

^interest  in  sex. 

f  Within  a  narrow  group,  of  course,  uniformity  of  conditions  may 
occasionally  act  to  reduce  natural  differences,  for  example  in  habits 
of  eating.  But  if  men  are  taken  over  all  the  world  and  over  a 
number  of  centuries  it  is  hard  to  find  any  trait  where  the  modifi- 
cations by  training  do  not  increase  natural  differences. 

The  second  law,  that  variations  are  greater  in  traits  peculiar  to 
man  than  in  traits  common  to  man  and  'the  mammals  in  general, 
is  evidenced  by  the  comparison  of  variability  in  remembering 
ideas  with  variability  in  remembering  acts  of  skill,  by  the  com- 
parison of  variability  in  marking  A's  with  variability  in  marking 
logically  absurd  sentences,  by  the  comparison  of  variability  in 
drawing  a  line  between  two  lines  accurately  with  that  in  defining 
a  word  accurately,  and  the  like.    As  the  superiority  of  the  best  to 

I  the  worst  philosopher  is  greater  than  that  of  the  best  to  the 
worst    rememberer    of    places    or    avoider    of    animal    enemies, 


Individual  Differences  in  Single  Traits  149 

so  the  variability  in  thinking  with  ideas  in  general  is  greater  than 
that  in  the  simple  sensori-motor  processes. 

The  Continuity  of  Mental  Variations 

Continuity  of  variations  means  two  things, — the  absence  of 
regularly  recurring  gaps,  such  as  those  between  2  petals,  3  petals, 
4  petals,  and  the  like,  and  the  absence  of  irregularly  recurring  gaps, 
such  as  those  between  mice  and  rats,  between  rats  and  squirrels, 
and  the  like. 

That  continuity*  of  variations  in  a  mental  trait  taken  singly  is 
the  rule  can  best  be  realized  by  trying  to  find  exceptions  to  it. 
Such  there  may  be,  but  I  am  not  aware  that  any  mental  trait 
varying  in  amount  has  been  shown  to  vary  by  discrete  steps.  A 
misleading  appearance  of  regularly  recurring  gaps  often  arises 
from  inadequate  measurements.  In  a  test  of  memory,  for  example, 
12  nonsense  syllables  being  read,  individuals  may  appear  in  the 
scores  as  5,  6,  7,  8  and  9  without  any  5.5's,  6.75's  and  the  like. 
But  if  four  such  tests  are  made  and  the  average  is  taken,  there 
will  be  5.5's  and  6.75's. 

A  misleading  appearance  of  irregular  discontinuity  often  arises 
from  the  insufficient  number  of  cases  measured.  If  only  a  few 
individuals  are  measured  in  a  trait  or  if  the  scale  is  a  fine  one, 
there  will  of  course  be  divisions  on  the  scale  or  amounts  of  the 
trait  unrepresented  in  any  individuals.  Thus  in  Fig.  26  (p.  145) 
there  are  such  gaps,  which  would  all  have  been  filled  in,  had  the 
number  of  individuals  been  very  large.  The  37  individuals  whose 
abilities  were  reported  in  Fig.  26  were,  in  fact,  chosen  at  random 
from  200.  If  all  the  200  records  had  been  used  in  constructing 
Fig.  26,  its  gaps  would  have  been  largely  filled  in.  For  example, 
the  37  cases  show,  between  the  abilities  500  and  700,  a  distribution 
as  in  the  upper  surface  of  Fig.  27,  whereas  the  200  cases  show, 

*0f  course  continuity  is  not  taken  here  in  the  sense  of  infinite 
divisibility.  There  are  doubtless  ultimately  unit-factors  which  either  act 
or  do  not  act,  and  which  consequently  increase  the  amount  of  the  trait 
by  either  zero  or  a  certain  amount.  But  the  discrete  steps  are  exceedingly 
small  like  the  steps  of  increase  of  physical  mass  by  atoms.  Intelligence, 
rate  of  movement,  memory,  quickness  of  association,  accuracy  of  discrimina- 
tion, leadership  of  men  and  so  on  are  continuous  in  the  sense  that  mass 
amperage,  heat,  human  stature  and  anemia  are. 


I50 


Educational  Psychology 


over  the  same  extent  of  the  scale,  a  distribution  as  in  the  lower 
surface  of  Fig.  2y. 

It  should  be  unnecessary  to  warn  the  reader  against  the 
absurdity  of  deliberately  changing  continuous  variations  into  a 
few  groups  by  coarse  scaling ;  next  assuming  that  the  central  part 
of  one  of  these  coarse  divisions  really  measures  all  the  individuals 
therein;  and  finally  imagining  that,  because  the  continuous  series, 
varying  from  a  to  a  +  b,  has  been  called,  say.  Poor,  Medium,  Good 


600 


500 


MO 


500 


Fig.  27.  The  distribution  of  the  cases  falling  between  500  and  700 
seconds  in  adding  48  columns  each  of  10  one-place  numbers,  when,  in  all, 
37  individuals  were  measured  (upper  diagram)  ;  and  when,  in  all,  200 
individuals  were  measured   (lower  diagram). 

and  Excellent,  there  are  really  gaps  within  it!     Unfortunately 
even  gifted  thinkers  are  guilty  of  this  error. 

The  Relative  Frequencies  of  Different  Amounts  of  Difference 

The  question  of  the  clustering  of  variations  around  one  central 
tendency  demands  more  elaborate  treatment.  Fig.  28  shows  the 
relative  frequencies  of  the  different  amounts  of  the  trait  in  the 
case  of  six  mental  traits.  These  six  distributions  illustrate  the 
statement  on  page  145  that  '  variations  usually  cluster  around  one 


Individual  Differences  in  Single  Traits 


151 


D 


Samples  of  the  forms  of  distribution  found  in  mental  traits. 


D 


Reaction  time :     252  college  freshmen. 

Memory  of  digits :     123  women  students. 

Efficiency  in  marking  A's  on  a  sheet  of  printed  capitals :  312  boys  from 

12  years  o  months  to  13  years  0  months. 
Efficiency  in  giving  the  opposites  of  words :  239  boys  from  12  years 

0  months  to  13  years  0  months. 

E.  Accuracy   in   drawing   lines   to   equal   a    100  mm    line :    153   girls    from 

13  years  0  months  to  16  years  0  months. 

F.  Efficiency  in  marking  words  containing  each  the  two  letters  a  and  t: 

312  boys  from  12  years  0  months  to  13  years  0  months. 
In  all  six  cases  the  left  end  of  the  scale  represents  the  lowest  abilities, — 
that  is,  the  longest  times  in  A,  the  fewest  digits  in  B,  etc.    The  continu- 
ous lines  give  the  distributions.    The  broken  lines  are  to  be  disregarded  for 
the  present. 


152 


Educational  Psychology 


central  tendency.'  This  statement  is  not,  however,  universally,  or 
even  commonly,  accepted.  On  the  contrary  the  common  opinion 
is  that  the  distribution  of  individuals  with  respect  to  the  amount 
of  a  single  trait  is  multimodal,  as  in  Fig.  29A,  or  even  a  compound 
of  entirely  distinct  species,  as  in  Fig.  29B.  There  would  then  be 
many  small  differences  and  many  large  differences  with  few  cases 
of  medium  differences.     This  may  be  called  the  '  multiple  type ' 


r-TU 


n 


£ 


Fig.  29.     Multimodal   distributions. 


theory.  For  instance,  in  the  case  of  intellect  we  find  the  terms 
genius,  normal,  feeble-minded,  imbecile  and  idiot  used  as  if  the 
geniuses  were  separated  by  a  clear  gap  from  the  normal 
individuals,  these  again  from  the  feeble-minded,  and  so  on.  So 
also  visualizers  and  non-visualizers,  or  men  of  normal  color  vision 
and  the  color  blind,  are  spoken  of  as  if  those  in  each  group  were 
all  almost  identical  and  all  much  unlike  all  in  the  other  grov.p. 

Multimodality  is  to  be  expected  in  traits  the  amount  of  which 
may  be  greatly  increased  or  decreased  by  some  one  cause   (or 


Individual  Differences  in  Single  Traits  153 

number  of  causes  commonly  acting  together).  If,  for  instance, 
reading  Aristotle  added  enormously  to  anyone's  intellectual  gifts, 
we  should  expect  to  find  men  divided  into  two  distinct  surfaces 
of  frequency  on  a  scale  for  intellect,  the  higher  ranking  species 
being  made  up  almost  exclusively  or  even  entirely  of  those  who 
had  taken  the  Aristotelian  dose.  The  action  of  ophthalmia  in 
causing  blindness  in  the  new-born  is  such  a  cause.  By  reason  of 
it  and  other  diseases,  the  visual  capacity  is  reduced  enormously 
in  certain  individuals,  so  that  there  are  two  modes,  the  seeing 
and  the  blind.  Fewer  men  are  able  just  barely  to  see  than  are 
totally  blind.  Injury  to  the  head  at  birth  or  disease  of  the 
thyroid  gland  may  be  such  a  cause,  reducing  certain  individuals 
all  to  an  equal  condition  of  intellect,  so  that  possibly,  by  reason 
of  it  and  other  accidents  and  diseases,  the  number  of  very  idiotic 
children  may  be  greater  than  the  number  of  those  less   idiotic 


Fig.  30.     A  distribution  showing  a  secondary  type,  of  great  inferiority. 

over  an  equal  length  of  the  scale  (see  Fig.  30),  This  is  doubtful, 
however. 

In  certain  traits,  such  as  knowledge  of  a  certain  language,  or 
ability  to  play  a  certain  game,  there  are  two  species.  One  includes 
those  who  have  had  no  opportunity  to  get  the  knowledge  or 
ability  and  whose  knowledge  or  ability  is  consequently  o ;  the  other 
is  made  up  of  those  who  have  had  some  opportunity  to  get  the 
knowledge  or  ability  and  who  range  in  it  from  o  or  near  o  to  a 
large  amount.  Understanding  of  spoken  English,  or  ability  to 
play  chess  or  whist  or  golf,  or  ability  to  typewrite  or  to  navigate 
a  ship  by  the  compass,  would,  of  course,  give  such  groups,  if 
measured  in  adults  the  world  over.  Here  the  cause  does  not 
produce  a  uniform  amount  of  the  trait,  but  the  uorld  is  so 
arranged  that  on  many  persons  the  cause  does  not  act  at  all. 

Many  such  causes  may  act  in  the  case  of  particular  habits, 


154 


Educational  Psychology 


knowledges  and  skills.  Since,  for  example,  some  Germans  are, 
and  some  are  not,  subjected  to  the  action  of  enforced  military 
service,  there  may  well  be  two  modes  to  the  surface  of  frequency 
of  knowledge  of  the  manual  of  arms,  one  group  all  knowing  it  very 
well,  the  other  group  knowing  hardly  anything  about  it.  Appren- 
ticeship to  a  certain  trade,  or  enrollment  in  a  certain  kind  of  school, 
may  thus  lead  to  extreme  and  uniform  amounts  of  knowledge  of, 
say,  plastering  or  typewriting  or  medicine,  so  as  to  divide  human 
nature  sharply  into  an  ordinary  and  an  expert  class.  How  far  this 
happens  is  not  known. 


Fig.  31.  Relative  frequencies  of  different  amounts  of  efficiency  in  mark- 
ing A's  on  a  printed  sheet  of  capital  letters,  in  the  case  of  a  group  of 
twelve-year-olds,  boys  and  girls  together. 

If  sex  made  a  great  enough  difiference  in  the  amount  of  any 
trait,  there  would  be  two  modes  in  the  surface  of  frequency  for 
the  trait  in  question  in  the  two  sexes  combined.  But  observable 
bimodality  as  a  result  of  mixture  of  the  sexes  does  not  in  fact 
appear,  because  the  sex  differences  are  so  small.  For  example, 
Fig.  31  shows  the  result  of  such  mixture  in  one  of  the  traits  in 
which  the  sexes  differ  most.  Figs.  32  and  33  show  the  distribution 
separately  for  each  sex. 

In  traits  in  which  race  makes  a  great  difference  there  will  tend 
to  be  a  mode  for  each  racial  type  if  two  extreme  races  are  mixed. 
Fig.  34  shows  the  results  of  so  mixing  civilized  Europeans  with 
Negritos  (Figs.  35  and  36  giving  the  separate  distributions  for 
Europeans  and  Negritos).  But  if  all  races,  or  a  random  selection 
of  races,  were  mixed  the  resulting  surface  of  frequency  would  not 
show  a  distinct  mode  for  each,  or  probably  for  any  one.     Even 


Individual  Differences  in  Single  Traits 


155 


so  great  a  difference  as  that  between  the  whites  and  the  colored 
in  scholarship  in  the  high  school  is  shown  in  the  combined  dis- 
tribution only  by  a  flattening  of  the  surface  of  frequency  as 
compared  with  that  of  either  race  alone  (see  Fig.  37). 


Fig.  32.  Relative  frequencies  of  different  amounts  of  efficiency  in  mark- 
ing A's  on  a  printed  sheet  of  capital  letters,  in  the  case  of  twelve-year-old 
boys. 


Fig.  32.  Relative  frequencies  of  different  amounts  of  efficiency  in  mark- 
ing A's  on  a  sheet  of  printed  capitals,  in  the  case  of  twelve-year-old  girls. 

In  traits  in  which  age  makes  a  great  difference,  there  will  be 
a  marked  flattening  of  the  surface  of  frequency.  Thus,  whereas 
for  any  one  age,  say  10  years  and  7  months,  the  variations  with 
respect  to  '  School  Grade  Reached  '  will  cluster  closely  around  one 
grade,  the  distribution  for  individuals  of  all  ages  from  8  years 
through  14  years,  shows  three  almost  equally  frequent  degrees  of 


156 


Educational  Psychology 


34 


7      17     27    37 


36 


7     17     27    37 


86 

7 

Figs. 


17    27    37 

34,  35  and  36.     Relative  frequencies  of  different  times  required  to 


insert  variously  shaped  blocks  in  holes  to  match.  The  best  abilities  (that 
is,  the  shortest  times)  are  at  the  left  end  of  the  scale  in  each  case.  Fig.  34 
gives  the  distribution  for  a  group  equally  divided  between  whites  and 
Negritos.    Fig.  35  is  for  whites  alone.    Fig  36  is  for  Negritos  alone. 


Individual  Differences  in  Single  Traits 


157 


the  trait.    This  fact  is  shown  in  the  case  of  the  boys  of  one  large 
city  in  Fig.  38. 

The  common  opinion  that  there  are  distinct  species  of 
individuals,  with  more  or  less  pronounced  gaps  between,  does  not, 
however,  limit  itself  to  presupposing  such  multimodalities  as  those 
made  by  men  and  women,  by  Germans  and  Bushmen,  by  five-year- 
olds  and  fifteen-year-olds,  by  the  ordinary  population  and  the  blind 
in  respect  to  vision,  by  plumbers  and  non-plumbers  in  respect  to 


Ln 


li  H 

Fig.  37.  The  relative  frequencies  of  different  degrees  of  high-school 
scholarship  in  a  group  composed  of  150  whites  and  150  negroes.  The 
lowest  grade  of  scholarship  is  at  the  left,  the  highest  grade  at  the  right,  end 
of  the  scale. 

skill  in  plumbing,  by  those  who  never  tried  to  learn  chess  and 
those  who  did,  in  respect  to  ability  at  playing  chess,  and  the  like. 
It  knows  little  or  nothing  of  the  effect  of  various  combinations  of 
causes  upon  the  form  of  distribution  of  a  trait  and  it  thinks  of 
men  as  divided  off  into  sharp  classes  in  mental  traits  chiefly 
because  it  has  not  thought  properly  about  the  question  at  all.  It 
merely  accepts  the  crude  adjectives  and  nouns  which  express 
primitive  awareness  of  individual  differences,  as  representatives  of 


158 


Educational  Psychology 


123466789  10 

Fig.  38.  The  relative  frequencies  of  different  degrees  of  progress  in 
school  in  the  case  of  boys  8  years  o  months  to  14  years  11  months  inclusive. 
The  horizontal  scale  at  the  bottom  is  for  'grade  reached,'  i,  2,  3,  etc.,  mean- 
ing first  grade,  second  grade,  third  grade,  etc.  The  surfaces  of  frequency 
are,  in  order  from  the  top  down,  for  8-year-olds,  g-year-olds,  lo-year-olds, 
1 1 -year-olds,  12-year-olds,  13-year-olds,  14-year-olds,  and  8-14-year-olds 
combined. 


Individual  Differences  in  Single  Traits 


159 


corresponding  divisions  in  reality ;  neglects  the  existence  of  inter- 
vening grades ;  and  does  not  even  attempt  to  estimate  the 
frequencies  grade  by  grade.  How  strong  this  tendency  to  verbal 
thinking  is  can  be  beautifully  illustrated  by  the  firm  conviction  of 
even  long-trained  men  of  science  that  people  are  either  markedly 
right-  or  markedly  left-handed,  are  either  '  normal '  in  color  vision 
or  far  removed  from  the  '  normal  '  in  color  weakness  or  color 


^-T 


C 


B 

Fig.  39.  The  distortion  of  the  form  of  distribution  due  to  the  presence 
of  too  few  cases.  A  is  the  distribution  as  found  from  several  hundred 
cases;  B  is  that  found  in  the  same  trait  from  the  first  28  of  them. 

blindness.  Until  recently  the  superstition  that  a  great  gulf  separ- 
ated children  of  normal  intellect  from  the  imbeciles  and  idiots  was 
also  very  strong  in  many  scientific  men.  The  multiple-type  theory 
does  not  refer  to  the  separation  of  individuals  into  groups  by  the 
presence  or  absence  of  some  one  cause,  or  closely  interrelated 
group  of  causes.  It  simply  vaguely  fancies  that  individuals,  even 
of  the  same  sex,  race,  age  and  training,  somehow  naturally  fall 
into  distinct  classes  or  '  types.' 


i6o  Educational  Psychology 

In  such  a  form  it  is  surely  almost  always,  if  not  always,  wrong. 
A  group  of  such  individuals  does  not,  as  a  rule,  show  a  separation 
into  two  or  more  groups,  all  in  one  being  much  like  each  other 
and  little  like  any  of  those  in  the  other  group,  or  groups.  Here 
again  the  rule  may  be  verified  by  searching  for  exceptions  to  it. 
I  know  of  no  such.  The  misleading  appearance  of  such  may  come 
either  (i)  from  inadequate  measurements,  as  in  the  case  of  the 
pseudo-discrete  variations,  or  (2)  from  the  examination  of  an 
inadequate  number  of  individuals.  Thus  ( i )  if  men  are  rated,  for 
sensitiveness  to  red  and  green,  as  color  blind,  color  weak  and  of 
'  normal '  color  vision,  there  will  appear  to  be  three  types,  just  as 
there  will  appear  to  be  three  types  of  stature  if  all  men  are  rated 
as  short,  medium  or  tall.  But  in  careful  tests  the  color  blind  will 
vary  among  themselves,  the  color  weak  likewise  and  the  '  normal ' 
likewise ;  the  color  blind  will  merge  imperceptibly  into  the  color 
weak  and  these  into  the  *  normal.'  Thus  (2)  if  only  fifty 
individuals  are  measured  and  if  the  scale  is  arranged  so  that  these 
are  included  by,  say,  twenty  divisions  of  it,  there  is  a  fair 
probability  that,  though  the  distribution  of  a  thousand  individuals 
show  a  clustering  around  one  type  as  in  Fig.  39A,  the  fifty 
may  be  clustered  around  two  or  more  types  as  in  Fig.  39B.  The 
absurdity  of  inferring  the  existence  of  two  species  of  human 
nature  with  respect  to  a  trait  from  two  apparent  modes  found 
when  only  a  few  individuals  are  studied  should  be  obvious. 

The  Chance  or  Probability  Distribution  in   the  Case  of  Single 

Mental  Traits 

In  sharp  contrast  to  the  common  notion  that  human  beings  are 
divided  sharply  into  classes,  is  the  theory  that,  for  any  one  trait, 
men,  at  least  by  original  nature,  form  always  only  one  class  defined 
by  one  single  sort  of  distribution.  This  theory  answers  in  the 
affirmative  the  questions :  "  Do  the  distributions  of  mental  traits 
in  groups  of  individuals  follow  any  regular  law?  Are  the  differ- 
ences between  individuals  in  mental  capacities  and  characteristics 
amenable  to  any  single  type  of  description?"  It  supposes  that, 
in  all  original  traits,  human  beings  so  differ  as  to  make  the 
distribution  that  of  a  chance  event,  the  surface  of  frequency  being 
that  of  the  probability  integral.  The  exact  meaning  of  this  sup- 
position and  the  basis  for  it  need  not  now  be  discussed.  Our  present 


Individual  Differences  in  Single  Traits 


i6i 


interest  is  in  discovering'  how  far  any  one  type  of  distribution  does 
characterize  all  original  mental  traits  in  human  beings.  By  using 
graphic  representations  rather  than  algebraic  formulae,  the  answer 
and  the  evidence  for  it  can  be  made  clear  even  to  one  who  knows 
nothing  whatever  of  the  mathematical  properties  of  the  surface 
of  frequency  of  a  chance  event  or  of  any  other. 

Fig.  40  gives  the  distribution  or  surface  of  frequency  of  the 
type  to  which  by  this  theory  the  distributions  of  natural  abilities 


Figs.  40  and  41.     The  'chance'  or  'probability'  form  of  distribution. 

conform.  Fig.  41  gives  the  same  distribution  as  Fig.  40,  but  with 
a  coarser  separation  into  grades. 

Before  comparing  actual  distributions  with  this  theoretical  form 
of  distribution  it  will  be  profitable  to  inquire  somewhat  more 
systematically  into  the  relation  between  the  factors  which  deter- 
mine the  amounts  of  a  trait  in  an  individual  and  the  relative 
frequencies  of  its  different  amounts  among  men. 

Suppose  the  amount  of  a  trait  to  be  determined  by  six  causes  or 
factors — a,  b,  c,  d,  e,  and  f — each  contributing  i  toward  it ;  and 
suppose  that  each  individual's  nature  includes  a  chance  drawing 


1 62  Educational  Psychology 

from  these  causes,  any  combination  being  equally  likely  to  be 
drawn. 

The  possible  combinations  are : — 

None 

a    b    c    d    e    f 

ab     ac    ad     ae    af    be    bd     be    bf    cd     ce    cf    de    df    ef 

abc    abd     abe    abf    acd     ace     acf    ade     adf     aef    bed 

bee    bcf    bde    bdf    bef    cde    cdf    cef    def 

abed    abce    abcf    abde    abdf    abef    aede    acdf    acef 

adef    bcde    bcdf    beef    bdef    cdef 

abcde    abcdf    abcef    abdef    acdef    bcdef 

abcdef 

Consequently  for  every  individual  possessing  o  units  of  the 
trait  there  will  be  6  possessing  6  units  of  it,  15  possessing  2  units, 
20  possessing  3  units,  15  possessing  4  units,  6  possessing  5  units, 
and  I  possessing  6  units.  The  relative  frequencies  of  the  different 
amounts  of  the  traits  will  be : — 


Amounts  of 
the    trait. 

Relative  frequencie 
of  these  amounts 

0 

I 

I 

6 

2 

15 

3 

20 

4 

5 
6 

15 

.6 

I 

Fig.  42  shows  the  form  of  distribution  graphically. 

Suppose  that  instead  of  six  such  causes  there  were  twenty.  The 
results  of  chance  drawings  from  the  possible  combinations  would 
then  be  to  give,  for  every  individual  possessing  o  units  of  the  trait, 
20  possessing  i  unit,  190  possessing  2  units,  1140  possessing  3 
units  and  so  on,  as  in  Table  19  and  Fig.  43. 

Suppose  the  number  of  causes  to  be  increased,  the  other  condi- 
tions remaining  as  before.  The  relative  frequencies  would  assume 
more  and  more  closely  the  proportions  shown  in  Fig.  40  (p.  161), 
which  is  the  surface  of  frequency  of  an  event  caused  by  a  chance 


Individual  Differences  in  Single  Traits  163 

TABLE  19. 

Form  of  Distribution  Resulting  from  Random  Combina- 
tions OF  20  Causes  of  Equal  Magnitude 


Amounts  of 

Relative  frequencie 

the    trait. 

of  these  amounts. 

0 

I 

I 

20 

.     2 

190 

3 

1,140 

4 

4,845 

5 

15,504 

6 

38,760 

7 

77,520 

8 

125,970 

9 

167,960 

10 

184,756 

11 

167,960 

12 

125,970 

13 

77,520 

14 

38,760 

15 

15,504 

16 

4,845 

17 

1,140 

18 

190 

19 

20 

selection  from  among  the  combinations  of  a  large  number  of  fac- 
tors each  of  small  and  all  of  equal  amount.  This  surface  is 
bounded  by  the  probability  curve.  It  is  often  called,  or  miscalled, 
the  '  Normal '  surface  of  frequency  or  '  Normal '  distribution 

The  distribution  of  individuals  in  certain  anatomical  traits  is 
much  like  that  of  Fig.  40.  The  close  fit  of  individual  variations 
in  stature  and  the  like  to  the  particular  bell-shaped  surface  of  the 
probability  integral  naturally  led  to  the  expectation,  or  at  least 
the  hope,  that  all  variable  facts  in  original  human  nature  would 
vary  in  this  one  way.  In  particular,  individuals  of  the  same  sex, 
age,  race  and  training  should  form  a  true  species  and  vary  in 
this  one  way. 


164 


Educational  Psychology 


As  a  matter  of  fact  they  do  not,  but  they  approximate  it.  No 
one  form  of  distribution  fits  them  all,  but  the  bell-shaped  curve 
given  by  the  equation  y=e-^^  fits  them  better  than  any  other 
simple  curve.  Fig.  28  (p.  151)  gives  fair  samples  of  the  closeness 
of  fit  in  mental  traits.*  The  condition  of  an  individual  in  a  trait 
is  very  often  the  result  of  something  approximating  a  chance 
selection  of  one  out  of  many  combinations  of  many  factors,  each 
of  small  and  nearly  equal  influence  on  the  trait's  amount.     In  so 


48 


Fig.  42.  The  'chance'  form  of  distribution  from  six  equal  and  indepen- 
dent causes. 

Fig.  43.  The  'chance'  form  of  distribution  from  twenty  equal  and 
independent  causes. 

far  as  it  is  so,  the  relative  frequencies  of  the  different  conditions 
of  individuals  in  respect  to  the  trait  will  be  approximately  those 
of  the  so-called  '  Normal '  surface  of  frequency.  But  just  as 
there  cannot  be  two  or  more  sharply  defined  types  unless  there 
are  certain  large  causes  whose  presence  makes  a  great  diflference 
in  the  trait's  amount,  so  there  cannot  be  a  very  close  approximation 
to  the  '  Normal '  sort  of  distribution  unless  the  causes  are  nearly 
independent,  and  of  nearly  equal  influence. 

*The  broken  lines  in  Fig.  28  give,  in  each  case,  the  '  chance '  form  of 
distribution. 


Individual  Differences  in  Single  Traits  165 

Such  a  trait  as  stature  shows  approximately  the  probabiHty  dis- 
tribution, because  its  amount  in  any  individual  is  determined  by 
many  only  slightly  correlated  causes,  such  as  the  thickness  of  the 
skull,  height  of  various  bones  of  the  head,  thickness  of  each 
of  the  vertebrae,  length  of  each  of  several  bones  in  the  leg,  and 
the  like.  Each  of  these  causes  is  again  determined  by  very  many 
imperfectly  correlated  causes.  But  such  a  trait  as  '  wealth  pos- 
sessed '  will  not.  For  certain  relatively  very  large  causes  are  at 
work,  such  as  the  discovery  of  a  mine,  or  the  death  of  rich  rela- 
tives ;  and  there  is  a  strong  correlation  between  many  of  the 
causes,  for  instance,  between  success  in  a  business,  directorship  in 
a  bank,  advanced  knowledge  of  important  actions,  and  power  to 
influence  these  actions. 

"  The  form  of  distribution  is  then  purely  a  secondary  result  of 
a  trait's  causation.  There  is  no  typical  form  or  true  form.  There 
is  nothing  arbitrary  or  mysterious  about  variability  which  makes 
the  normal  type  of  distribution  a  necessity,  or  any  more  rational 
than  any  other  sort  or  even  any  more  to  be  expected  on  a  priori 
grounds.    Nature  does  not  abhor  irregular  distributions. 

On  a  priori  grounds,  indeed,  the  probability  curve  distribution 
would  be  exactly  shown  in  any  actual  trait  only  by  chance.  For 
only  by  chance  would  the  necessary  conditions  as  to  causation  be 
fulfilled.  And,  in  point  of  fact,  as  the  reader  has  constantly  been 
told  by  the  adjective  '  approximate,'  the  exact  probability  curve 
distribution  does  not  appear  in  the  facts  or  give  signs  of  being 
at  the  bottom  of  the  facts  of  mental  life.  The  common  occurrence 
of  distributions  approaching  it  is  due,  not  to  any  wonderful  tend- 
ency of  a  group  of  cooperating  causes  to  act  so  as  to  mimic  the 
combinations  of  mathematical  quantities  equal  and  equally  prob- 
able, but  to  the  fact  that  many  traits  in  human  life  are  due  to 
certain  constant  causes  plus  many  occasional  causes  largely  un- 
related, small  in  amount  in  comparison  with  the  constant  causes 
and  of  the  same  order  of  magnitude  among  themselves."  [Thorn- 
dike,  '04,  p.  69  f.] 

Distributions  approximating  it  do  occur  very  commonly  in 
mental  traits  of  original  nature.  And  one  will  probably  never  be 
far  misled  by  supposing  that,  in  respect  to  the  amount  of  original 
endowments  in  any  trait,  individuals  of  the  same  sex,  race  and 
age  are  distributed  approximately  according  to  the  probability 
surface.     The  evidence  from  measurements  points  toward  such 


i66 


Educational  Psychology 


approximation.  Moreover,  what  is  known  of  the  physical  basis 
of  intellect  and  character  leads  to  the  expectation  that  many 
somewhat  nearly  equal  factors  are  at  work  to  determine  the 
amount  of  any  instinct  or  capacity  possessed  by  men. 

The  meaning  of  some  of  the  cases  where  the  distribution  of 
mental  traits  does  not  approximate  the  chance  distribution  will 
become  clear  if  we  examine,  first,  some  cases  of  the  distribution 
of  a  trait  in  a  group  of  individuals  of  two  or  more  distinct  degrees 
of  maturity  or  of  training,  and,  second,  cases  where  some  selective 


J 


Zna 


Z 


46  47 

Figs.  44-47.  The  effect  upon  the  form  of  distribution  due  to  combining 
groups  distinct  in  respect  to  age,  training  or  some  other  cause  affecting  the 
trait  in  question. 

Fig.  44.  The  distribution  of  ability,  in  the  A  test,  of  children  8,  9,  14 
and  15  years  old. 

Fig.  45.  The  distribution  of  ability,  in  the  opposites  test,  of  children 
from  grades  3  and  7. 

Fig.  46.  The  distribution  of  ability,  in  multiplication,  of  children  from 
grade  7  and  high  school. 

Fig.  47.  The  distribution  of  ability,  in  the  a-t  test,  of  children  9  and  IS 
years  old. 

agency  has  been  at  work.  Fig.  44  gives  the  distribution  of  ability 
in  the  A  test  in  a  group  of  children  8,  9,  14  and  15  years  old.  Fig. 
45  gives  the  distribution  of  ability  in  writing  the  opposites  of 


Individual  Differences  in  Single  Traits 


167 


'61 


d 


IS 


62 


u 


63 


64 

Figs  48-54.  The  effect  upon  the  form  of  distribution  due  to  the 
selection  of  individuals  in  relation  to  causes  affecting  the  amount  of  the 
trait  in  question.  The  left  end  of  the  scale  is  for  the  lowest  degree  of  the 
trait  in  each  case. 

Fig.  48.  The  distribution  of  ability,  in  controlled  association,  of  12-year- 
old  boys  in  the  6A  grade  or    higher. 

Fig.  49.  The  distribution  of  ability,  in  controlled  association,  of  12-year- 
old  boys  in  the  6B  grade  or  lower. 

Fig.  50.  The  distribution  of  ability,  in  controlled  association,  of  all 
12-year-old  boys  in  the  school. 

Fig.  51.  The  distribution  of  ability,  in  mathematics,  of  candidates  for 
honors  in  mathematics  at  Cambridge  University. 

Fig.  52.  The  distribution  of  ability,  in  marking  A's,  of  university  teachers 
and  students. 

Fig.  53.  The  distribution  of  ability,  in  memory,  of  university  teachers 
and  students. 

Fig.  54.  The  distribution  of  ability,  in  giving  the  opposites  of  words,  of 
inferior  day-laborers. 


1 68  Educational  Psychology 

words  in  a  group  composed  of  about  140  girls  in  the  third  school 
grade  and  about  180  girls  in  the  seventh  school  grade.  Fig.  46 
gives  the  distribution  of  ability  in  multiplication  in  a  group  com- 
posed of  seventh  grade  pupils  and  high  school  pupils.  Fig.  47 
gives  the  distribution  of  ability  in  marking  words,  containing 
each  the  two  letters  a  and  t,  in  a  group  comprising  9-year-olds  and 
15-year-olds.  In  general  when  the  surface  of  frequency  of  a 
mental  trait  departs  from  the  probability  curve  toward  a  flatten- 
ing and  toward  the  appearance  of  two  or  more  modes,  one  may 
expect  to  find  a  mixture  of  sexes,  races,  ages  or  trainings. 

Fig.  48  gives  the  distribution  in  a  test  of  controlled  association 
of  the  12-year-old  boys  in  the  6A  grade  or  higher.  The  lack  of 
symmetry  in  the  surface  is  obviously  due  to  the  fact  that  we  are 
dealing  with  a  selected  group — that  the  duller  and  less  mature 
boys  have  been  eliminated.  The  influence  of  the  opposite  sort  of 
elimination  is  seen  in  Fig.  49,  which  gives  the  distribution,  in  the 
same  trait,  of  12-year-old  boys  in  the  grades  lower  than  the  6A. 
By  combining  the  two  we  have  Fig.  50,  which  approximates  the 
chance  distribution.  Fig.  5 1  gives  a  real  case  of  a  distribution  dis- 
torted by  selection.  It  is  the  distribution  of  mathematical  ability 
in  the  candidates  for  honors  in  mathematics  at  Cambridge  Univer- 
sity.* Of  course  such  candidacy  implies  that  the  poorer  grades 
of  mathematical  ability  are  eliminated.  Figs.  52  and  53  represent 
the  distribution  of  ability,  in  marking  A's  and  in  immediate  memory 
of  lists  of  words  respectively,  in  seventeen  university  teachers  and 
students,  while  Fig.  54  represents  the  distribution  of  ability  in 
the  '  opposites '  test  in  the  case  of  twenty  day-laborers  of  inferior 
sort.  Any  selective  agency  which  works  upon  a  species  of  indi- 
viduals will  alter  the  shape  of  the  surface  of  frequency  for  any 
mental  trait,  unless  its  selections  are  random  with  respect  to  dif- 
ferent amounts  of  that  trait.  As  the  selective  action  is  commonly 
such  as  picks  out  the  good  or  the  bad,  the  result  is  commonly  to 
produce  a  '  skewness '  of  the  surface  toward  one  extreme  and  a 
blunted  condition  at  the  other.  When  a  series  of  measurements 
in  a  group  of  the  same  sex,  age  and  training  shows  a  deviation 
from  the  probability  surface  toward  conditions  like  those  of  Figs. 
55  and  56,  it  is  wise  to  ascertain  whether  some  selective  agency 
has  not  been  at  work  upon  the  group. 

We  have  seen  that  the  form  of  distribution  of  a  single  mental 

*It  is  taken  from  Gal  ton's  Hereditary  Genius, 2d  ed.  p.  16. 


Individual  Differences  in  Single  Traits  169 

trait  is  usually  such  that  the  individuals  cluster  around  one  cen- 
tral tendency.  We  have  seen  also  that,  within  a  group  of  the 
same  sex,  race  and  age,  in  original  traits,  the  variations  from 
the  central  tendency  occur  in  approximately  the  relative  frequen- 
cies described  by  the  probability  distribution.  A  deviation  of  any 
degree  plus  is  about  as  common  as  that  of  the  same  degree  minus ; 
or,  more  briefly,  the  distribution  is  approximately  symmetrical. 
The  average,  median  and  mode  therefore  nearly  coincide.  The 
frequency  decreases  with  the  amount  of  deviation  from  the  cen- 
tral tendency,  at  first  slowly,  then  rapidly  and  then  slowly.    The 


Figs.  55  (above)   and  56  (below). 

average  deviation  from  the  central  tendency  is  about  1.18  times 
the  median  deviation.  About  82  per  cent  of  the  individuals  differ 
from  the  C.  T.  by  less  than  2  times  the  median  deviation ;  about 
96  per  cent  by  less  than  3  times  the  median  deviation ;  about  99^ 
per  cent  by  less  than  4  times  it. 

The  most  important  fact,  however,  is  not  the  commonness  of 
this  or  that  form  of  distribution,  but  the  absolute  law  that  the 
-form  of  distribution  is  a  result  of  the  nature  of  the  factors  at  work 
to  produce  the  trait's  amount.  One  large  factor  that  is  present 
for  some  individuals  and  not  for  others  will  always  act  toward 
the  production  of  bimodality  or  distinct  types.  A  multitude  of 
nearly  equal  factors  from  which  each  man's  nature  and  training 


170  Educational  Psychology 

is  approximately  a  random  selection  will  always  act  toward  the 
production  of  unimodality,  symmetry,  and  slow-rapid-slow  de- 
crease in  frequency  around  the  central  tendency.  An  interde- 
pendence whereby  the  action  of  certain  factors  increasing  the 
amount  of  the  trait  is  dependent  upon  the  action  of  other  factors 
which  of  themselves  bring  the  individual  to  a  certain  fairly  high 
station,  will  always  act  to  disturb  symmetry.  For  every  peculiar- 
ity in  the  causes  determining  a  trait's  amount  in  an  individual 
there  will  be  an  effect  in  the  relative  frequencies  of  the  trait's 
amounts  in  a  group  of  individuals. 

I  should  perhaps  apologize  to  the  reader  for  this  long  discus- 
sion of  a  matter  which  may  seem  to  be  sufficiently  obvious  with- 
out any  discussion.  I  am  glad  if  it  does  now  seem  obvious.  The 
excuse  for  the  long  discussion  is  that  the  usages  of  language  have 
persistently  misled  thinkers  about  human  nature  into  supposing 
that  it  was,  in  each  trait,  divided  into  sharply  separated  classes  to 
fit  the  adjectives  and  nouns  by  which  primitive  man  roughly  de- 
noted different  sections  of  a  continuous  scale,  and  that,  on  the 
other  hand,  certain  thinkers  have  carelessly  extended  the  particu- 
lar '  probability '  form  of  distribution  to  cases  where  it  cannot 
possibly  fit  the  facts. 


CHAPTER  IX 

The  Relations  Between  the  Amounts  of  Different  Traits 
IN  THE  Same  Individual 

One  feels  a  bareness  and  paltriness  in  such  piecemeal  descrip- 
tions of  human  beings  and  their  differences  one  from  another  as 
have  been  given  in  the  last  chapter.  The  actual  varieties  of  hu- 
man nature  do  not  stand  out  when  one  trait  at  a  time  is  measured. 
Why,  it  may  be  asked,  does  psychology  not  take  actual  whole  na- 
tures and  state  how  they  differ?  Why  does  psychology  not  de- 
scribe human  minds  as  zoology  describes  animal  bodies,  by  classi- 
fying them  into  families,  genera  and  species,  and  by  stating  the 
differences  between  the  different  sorts  of  minds  found? 

It  is  true  that  zoology  does  not  measure  all  animals  in  length, 
then  in  weight,  then  in  color,  then  in  number  of  organs,  then  in 
number  of  bones,  and  so  on  through  a  list  of  particular  traits.  It 
began  with  types  or  sorts  apparent  to  common  observation,  such 
as  worms  and  fishes,  and  described  their  essential  features  and 
the  characteristic  differences  of  one  sort  from  another.  And  it  is 
true  that  psychology  might  try  to  do  likewise.  If  there  were  types 
or  sorts  of  minds  equally  apparent  to  common  observation,  it 
would  surely  be  worth  while  to  start  a  description  of  human  na- 
ture's varieties  with  them.  But  there  are  no  sorts  or  types  of 
minds  that  stand  out  clearly  as  birds,  fishes  and  worms  do  amongst 
animal  forms.*  Psychology  has  first  to  find  which  the  sorts  or 
types  are. 

There  are  two  ways  of  discovering  them.    The  first  is  by  direct 

*The  men  allied  by  common  ancestry,  men  of  the  same  race,  would  be 
most  likely  to  form  a  mental  sort  or  type  differing  from  other  men,  if  not 
as  fishes  differ  from  other  animals,  at  least  as  much  as  salmon  differ  from 
other  fishes.  But  even  between  races  there  is  no  surety  that  such  is  the 
case  and  no  excuse  for  avoiding  the  slow  and  laborious  comparison  of 
individuals  from  different  races  in  one  after  another  trait  that  seems 
significant. 

(171) 


172  Education€.l  Psychology 

measurement  of  individuals  in  toto,  and  of  their  differences.  To 
measure  the  difference  between  one  whole  man  and  another 
means  to  assign  to  each  man  his  amount  of  each  trait,  and  to 
measure  each  difference.  The  difference  between  the  two  men 
means  just  all  those  particular  differences.  To  this  method  we 
shall  return  in  the  next  chapter,  though  it  may  be  said  at  once 
that  no  adequate  total  measurements  exist  of  even  a  single  indi- 
vidual. 

The  second  way  of  discovering  the  sorts  or  types  into  which 
men  as  total  natures  are  divided  is  by  discovering  what  each 
amount  possessed  of  any  one  trait  implies  concerning  the  individ- 
ual's condition  in  other  traits. 

A  statement  of  the  differences  between  one  whole  man  and 
another  would  be  an  almost  interminable  inventory  of  particular 
differences,  unless  some  traits  were  so  related  that  knowledge  of 
the  amount  of  one  of  them  possessed  by  a  man  informed  us  of  the 
amount  he  possessed  of  the  other  also.  Suppose,  for  instance,  that 
any  given  amount  of  error  in  judging  one  length  with  the  eyes 
always  implied  certain  known  amounts  of  error  in  judging  all 
lengths,  whether  by  eye,  by  arm-movement  or  by  pressure,  all 
weights,  all  colors,  all  pitches,  all  tastes,  all  smells,  all  bright- 
nesses, all  intensities  of  sound  and  all  other  sensory  features  of 
objects.  In  such  case,  one  measurement  would  inform  us,  once 
for  all,  of  a  fairly  large  fraction  of  a  man's  nature  and  of  his 
differences  from  another  man,  similarly  measured.  The  necessary 
preliminary  to  the  direct  study  of  differences  of  total  natures  is 
thus  the  study  of  the  relations  of  single  mental  traits. 

The  Measurement  of  Relations  between  Mental  Traits 

It  is  necessary  to  be  clear  at  the  outset  in  respect  to  just  what  is 
meant  by  the  relation,  or,  as  it  is  commonly  called,  the  correlation, 
between  two  mental  traits.  It  means,  of  course,  the  relation  of 
some  amount  of  one  trait  (A)  to  some  amount  of  another  trait 
(B).  It  also  means,  for  the  present  purpose,  the  relation  between 
an  amount  of  A  characteristic  of  a  given  individual  to  an  amount 
of  B  characteristic  of  that  same  individual.  The  amounts  might 
be  the  amount  of  A  more  than  zero  and  the  amount  of  B  more 
than  zero;  or  they  might  be  the  amount  of  A  more  than,  or  less  than, 
some  assigned  amount  and  the  amount  of  B  more  than,  or  less 


Relations  Between  Mental  Traits  173 

than,  some  assigned  amount.  Let  us  call  the  first  sort  relations  of 
divergences  from  and  the  second  part  relations  of  divergences 
from  arbitrary  standards,  or  arbitrary  relations. 

For  example,  suppose  5  eight-year-old  girls,  I,  II,  III,  IV  and  V, 
in  tests  of  memory  of  German  equivalents  of  English  words,  to 
show  the  following  abilities : — 


Trait  A 

Trait  B 

Individual 

Median  number  of  words 

remembered  (after  a  given 

amount  (K)  of  training) 

at  the  end  of  2  minutes. 

Median  number  of  words 

remembered  (after  a  given 

amount  (K)  of  training) 

at  the  end  of  60  days. 

I. 

23 

II 

II. 

21 

II 

III. 

16 

9 

IV. 

II 

3 

V. 

9 

5 

In  the  first  meaning,  the  relation  of  the  divergence  from  zero 
is,  of  course,  expressed  as  ^^,  ^,  ^\,  ^  and  f ,  respectively 
for  these  children.  The  central  tendency  of  the  relation  is, 
roughly,  to  remember  half  as  much  after  two  months  as  was 
remembered  after  two  minutes. 

Suppose,  now,  that  the  relation  sought  is  that  between 
divergence  from  the  central  tendency  for  eight-year-old  girls  in  A 
and  divergence  from  the  central  tendency  for  eight-year-old  girls  in 
B,  and  that  this  central  tendency  is  15  for  A  and  6  for  B.     The 

w               ^x,       +5+5+3-3  -I 

relations  are  then  - — ^,  -; — 7.  ~; — .  and 


+  8'   +6'   +11'    -4  -6' 

Suppose  that  the  relation  sought  is  that  between  divergence  from 

the  central  tendency  of  all  human  beings  in  A  and  divergence  from 

the  central  tendency  of  all  human  beings  in  B,  and  that  these  central 

tendencies  are  24  for  A  and  10  for  B.     The  relations  are  then 

,  ,  — —,   and  .     It  is  clear  that  any  relation 

-  I  '    -3'    -8'    -13  -15  ^ 

varies  according  to  the  standards  from  which  the  related  diverg- 
ences are  measured. 

The  relations  to  be  considered  in  this  chapter  are  arbitrary 
relations.  We  shall  always  be  concerned  with  the  relation  of  an 
individual's  divergence  from  the  central  tendency  of  some  defined 
group  in  one  trait  to  his  divergence  from  the  central  tendency  of 
that  same  group  in  another  trait. 


174  Educational  Psychology 

The  first  fact  to  notice  about  such  mental  relations  is  that  the 
same  relation  varies  greatly  in  different  individuals.  Such  a  case 
as  that  of  the  last  illustration,  in  which  the  relations  were,  for 
five  individuals,  -i.oo,  -.33,  +.125,  +-54,  and  +.33,  is  not  at  all 
exceptional.  The  relations  of  traits  differ  in  individuals  as  truly 
as  do  the  amounts  of  a  trait.  A  single  sample  will  suffice.  Fig.  57 
shows  the  relation  of  (A)  divergence  from  the  central  tendency 
of  adult  college  women  in  drawing  a  line*  to  equal  a  50  mm.  line 


-50   -30   -10   +10   +30   +60   +70  +170 


.90 
-70 
-60 
-80 
-10 
+10 
+80 
+60 
+70 


•«90 

Fig.  57.  The  relation  between  ability  in  equalling  a  so  mm.  line  (average 
of  30  trials)  and  ability  in  equalling  a  lOO  mm.  line  (average  of  30  trials), 
in  women  students. 

to  (B)  divergence  from  the  central  tendency  of  the  same  group 
in  drawing  a  line*  to  equal  a  lOO  mm.  line.  Each  dot  represents 
the  relation  in  one  individual  by  its  location.  Each  dot  is  below 
the  point  (on  the  scale  for  A)  which  is  the  individual's  measure 
in  A  and  opposite  the  point  (on  the  scale  for  B)  which  is  the 
individual's  measure  in  B. 

♦Under  certain  specified  conditions. 


Relations  Between  Mental  Traits  175 

It  is  at  once  seen  that  superiority  of  an  individual  to  the  central 
tendency  of  adult  college  women  in  A  does  in  general  imply 
superiority  to  their  central  tendency  in  B,  but  that  there  is  a 
wide  range  in  the  relation  in  individual  cases.  If  the  relation  had 
been  the  same  in  all  individuals,  the  dots  would  all  be  on  one  line, 
since  all  the  individuals  under  any  one  point  of  the  horizontal 
scale  (that  is,  of  the  same  ability  in  A)  would  all  be  opposite  the 
same  point  of  the  vertical  scale. 

Since  the  relation  does  vary  with  individuals,  it  is  fully  measured 
or  described  only  by  such  a  list  of  all  the  individual  relations  as 
Fig.  57  gives.  But  its  main  features  can  be  summarized,  for  any 
one  degree  of  trait  A,  in  two  measures,  one  of  the  central  tendency 
of  all  these  individual  relations,  and  the  other  of  their  variability 
around  this  central  tendency. 

Thus,  suppose  10  individuals,  all  -8  in  Trait  A,  to  be,  respec- 
tively, -  12,  -  7,  -  5,  -  5,  -  4,  -  4,  -  2,  -  I,  o  and  +6  in  Trait 

—  12-7-5  — 4 

B.     The  median  of  the  ratios  3^  ,  "j^.  ITq"'  ^^^'  ^®  3~r~'  ^^ 

+  .5.  The  central  tendency  of  the  relation  is  for  -  8A  to  imply  -  4B. 

The  variability  ranges  from  an  implication  of  -  12  to  one  of  +  6 

The  relation  may  also  vary  with  different  individuals  according 

to  the  amounts  of  A  which  they  have.     Thus,  suppose  that  the 

central  tendency  in  the  case  of  individuals  all  having  +16 A  was 

-2 
to  the  relation  — y^-     The  +  .5  which  restated  the  central  tendency 

of   the  relation  for  individuals  of  -  8A,    is  replaced   by  -  .125. 

Fig.  58  shows  a  case  (hypothetical)  of  a  relation  varying  much 
with  the  amount  of  trait  A,  but  with  very  little  variation  amongst 
individuals  of  like  ability  in  A. 

Fig.  59  shows  a  case  (also  hypothetical)  of  a  relation  varying 
little  with  the  amount  of  trait  A,  but  much  amongst  individuals 
of  like  ability  in  trait  A. 

Fig.  60  shows  a  case  (also  hypothetical)  of  a  relation  varying 
much  in  both  respects. 

In  these  figures  the  line  formed  by  the  points  representing  each 
the  central  tendency  of  the  relation  in  the  case  of  one  amount  of  A 
may  be  called  the  relation  line.  In  Figs.  58,  59  and  60,  it  is  the 
line  formed  by  the  large  dots. 

When  a  relation  varies  according  to  the  amount  of  one  of  the 
traits, — when,  that  is,  the  central  tendency  of  the  ratio  A/B 


176 


Educational  Psychology 


Amount      tf   Tri'lt    A 


^  .;:•. 


eo    ;.;• 


I 


,  •• 


*    I*  •* 
,s  r . I  . 


*■■•*••• 

Fig.  58.    A  relation  varying  much  with  different  amounts  of  Trait  A, 
but  varying  little  amongst  individuals  of  like  ability  in  A. 


AmouftT    of  Trait    A  -H >• 


t 


I 


t    :    '•     ' 


Fig.  59.    A  relation  varying  little  with  different  amounts  of  A,  but  much 
amongst  individuals  of  like  ability  in  A. 

is  different  for  A=k,  A=2k,  A=3k,  etc., — it  may  be  called  non- 
rectilinear,  because  the  relation  line  is  curved  or  broken.  When 
a  relation  varies  with  individuals  irrespective  of  their  amounts  of 


Relations  Between  Mental  Traits 


177 


Trait  A,  the  central  tendency  of  the  A/B  ratio  being  the  same 
for  all  values  of  A,  it  may  be  called  rectilinear  because  the  relation 
line  will  be  a  straight  line. 

When  only  a  few  individuals  are  studied,  so  that  the  number  at 
any  given  point  on  the  scale  for  A  is  not  enough  to  give  reliably 
the  central  tendency  of  the  relation  at  that  point,  the  relation  will 


-it      of       /rd.t      A 


j  -  • 


Fig.  60.    A  relation  varying  much  in  both  respects. 

Figs.  58-60.     The  variability  of  mental  relations. 
Trait  A  is  scaled  horizontally,  the  lowest  degree  being  at  the  left. 
Trait  B  is  scaled  vertically,  the  lowest  degree  being  at  the  top. 
Each    dot    represents    the    relation    in   one    individual,    the    amount   of    A 
possessed  by  the   individual  being  that  represented  by  the  point  on  the 
scale  for  A  above  the  dot,  and  the  amount  of  B  possessed  by  the  individual 
being  that  represented  by  the  point  on  the  scale  for  B  at  the  left  of  the  dot. 
The    large    dots    represent,    each   by   its   position,    the    central    tendencies 
(medians)  of  those  of  each  degree  of  ability  in  A. 

appear  non-rectilinear  even  though  it  may  really  be  rectilinear. 
For  example,  the  relation  between  ability  in  the  A  test  and  ability 
in  the  a-t  test  in  12-year-old  boys  (divergences  from  C.  T.'s  for 
that  age  and  sex  being  related)  is  really  rectilinear  or  very  nearly 
so,  but  the  relation  line  for  any  100  boys  will  seem  to  be  much 
broken  as  in  Fig.  61.  Whatever  be  the  real  form  of  the  relation 
line,  chance  deviations  from  that  form  will  appear  unless  the  num- 


178 


Educational  Psychology 


ber  of  cases  is  infinitely  large.  But  in  reality  sharply  irregular 
relations  with  zigzag  relation  lines, — such  relations  for  instance  as 
.5  for  A  =  k,  .7  for  A  =  k+ I,  .3  for  A  =  k  +  2,  .5forA  =  k  +  3, 
.4  for  A  =  k  +  4,  .6  for  A  =  k+5,  .5  for  A  =  k  +  6,  and  so  on 
— probably  do  not  exist  between  any  mental  traits. 

Relationships  with  curvilinear  relation  lines  deviating  markedly 
from  straight  lines, — such  as  that  in  Fig.  58  or  those  in  Fig.  62, — 
may  exist,  but  no  such  relation  has  as  yet  been  proved  to  exist. 
It  is  therefore  customary  to  treat  relations  between  mental  traits 
as  approximately  rectilinear. 

The  relation  of  two  traits  in  a  given  group  of  individuals  being 
expressed  as  the  rectilinear  relation  which  best  fits  them,  their 
relation  can  be  compared  with  that  of  any  other  traits  in  the  same 
or  any  other  group — provided  one  more  simplification  be  made. 


-10      -8       -6       -4-2         0       -ta       +4       +e       +8      +10      tI2      +14 

Fig.  61.  The  relation  line  in  the  case  of  the  relation  between  abiHty  in 
marking  A's  (one  trial  of  60  seconds)  and  ability  in  marking  words  con- 
taining both  a  and  t  (one  trial  of  120  seconds),  in  the  case  of  girls  of  the 
same  school  grade.  (With  more  adequate  tests  the  relation  would  be  much 
closer  and  the  relation  line  somewhat  straighten) 

This  is  that  the  divergences  to  be  related  be  expressed  each  as  a 
fraction  of  the  variability  of  the  trait  in  question.  For  example, 
suppose  A,  B,  C  and  D  to  be  series  of  divergences,  in  height, 
weight,  memory  of  words  in  a  certain  test,  and  ability  in  the  A  test, 
from  the  condition  of  the  modal  twelve-year-old  boy.  Suppose 
that  the  central  tendencies  of  the  ratios  A/B,  A/^C  and  A/D 
were  respectively  .5,  .2  and  .5.  That  would  mean  that  a  boy  ten 
centimeters  above  the  central  tendency  would  in  the  long  run  be 
5  kilograms  heavier,  remember  2  words  more,  and  mark  5  A's 


Relations  Between  Mental  Traits  179 

more,  than  the  modal  twelve-year-old  boy.  This  does  not  enable 
one  to  tell  whether  A/B  is  really  equal  to  the  relation  A/D, 
though  each  is  .5.  Nor  can  one  say  with  any  useful  meaning  that 
A/B  is  two  and  one-half  times  as  close  a  relation  as  A/C. 


Fig.  62.     Samples  of  curvilinear  relation  lines. 

But  if,  instead  of  calculating  the  gross  A/B,  A/C  and  A/D 
ratios  (.5,  .2  and  .5),  we  calculate  the  values  of  these  rat'os  after 
every  value  of  A  is  expressed  as  a  multiple  of  the  variability  of 
twelve-year-old  boys  in  trait  A,  every  value  of  B  is  expressed  as 


i8o  Educational  Psychology 

a  multiple  of  the  variability  of  twelve-year-old  boys  in  trait  B  and 

so  on,  the  ratios  become  commensurate. 

Suppose  the  variabilities  of  twelve-year-old  boys  in  the  four 

traits  to  be,  respectively: — Var.  A,  4.5  centimeters;  var.  B,  3.5 

pounds  ;  var.  C.  2.0  words  ;   var.  D,  4.5  A's.     Then  the  central 

-   ,  .      A /var.  A     A/var.  A       ,  A /var.  A      .„ 

tendencies  of  the  ratios,  r-^7 —,  ^^-^^ ^  and  .pr =,  will 

B/var.  B    C/var.  C  D/  var.  D 

be  .4,  .09  and  .5.*    The  .4,  .09  and  .5  will,  in  each  case,  mean  the 

same  thing,  if  'equal  multiple  of  the  variability'  of  any  one  trait 

is  regarded  as  always  the  same  thing.     They  will  mean,  in  each 

case,  the  relation  of  (I.)  an  individual's  divergence  in  one  trait 

measured  as  a  multiple  of  the  general  tendency  to  diverge  in  that 

trait,  to  (II.)  his  divergence  in  another  trait,  measured  likewise 

as  a  multiple  of  the  general  tendency  to  diverge  in  that  trait. 

It  is  with  such  a  meaning  that  we  compare  the  closeness  of  the 
relation  between,  say,  memory  for  numbers  and  memory  for 
words  with  the  closeness  of  the  relation  between  memory  for  the 
same  data  over  a  short  and  over  a  long  interval ;  or  compare  either 
of  these  with  the  relation  between  accuracy  of  discrimination  of 
length  and  accuracy  of  discrimination  of  weight. 

If  each  divergence  is  expressed  in  terms  of  the  variability  of 
its  trait  as  a  unit,we  can  think  of  an  individual's  condition  in  one 
trait  as  resembling  or  differing  from  his  condition  in  another 
trait.  The  technique  of  measuring  this  resemblance  between  two 
traits  in  one  man  is  then  the  same  as  that  made  familiar  in  Chap- 
ter V  in  the  case  of  the  resemblance  of  two  individuals  in  the 
same  trait.  R,  the  coefficient  of  resemblance,  then  measures  the 
central  tendency  to  resemblance  or  mutual  implication  found  in 
pairs  of  amounts  or  conditions  in  two  traits,  each  pair  being 
characteristic  of  an  individual.  The  amounts  are  divergences 
from  the  central  tendencies  of  some  defined  group.  The  relation 
or  resemblance  or  mutual  implication  is  supposed  to  be  constant 
for  all  amounts  of  either  trait.  R  is  a  figure  so  calculated  from 
the  individual  records  as  to  give  the  one  degree  of  relationship 
between  the  two  traits  which  will  best  account  for  all  the  sepa- 
rate cases  in  the  group.  In  other  words  it  expresses  the  recti- 
linear relation  from  which  the  actual  cases  might  have  arisen  with 

*  A  ^  var.  A  _  Ay  ^^''•^or.sX^   or  .4.      Similarly    for     the    .09 
B  -f-  var.  B  B        var.  A  4.5 

and  .5. 


Relations  Between  Mental  Traits  i8i 

least  improbability.  It  has  possible  values  from  +i,oo  through  o 
to  —  i.oo.  'R==+i.oo'  means  that  the  individual  who  is  the 
best  in  the  group  in  one  ability  will  be  the  best  in  the  other,  that 
the  worst  man  in  the  one  will  be  the  worst  in  the  other,  that  if 
the  individuals  are  ranked  in  order  of  excellence  in  the  second, 
the  two  rankings  will  be  identical,  that  anyone's  divergence 
in  the  one  will  be  identical  with  his  divergence  in  the  other  (both 
being  reduced  to  multiples  of  the  variabilities  of  the  abilities  to 
allow  comparison).  'R  =  -i.oo'  would,  per  contra,  mean  that 
the  best  person  in  the  one  ability  would  be  the  worst  in  the 
other,  that  any  degree  of  superiority  in  the  one  would  go  with 
an  equal  degree  of  inferiority  in  the  other.  '  R  =  +  .62  '  would 
mean  that  (the  two  series  of  divergences  being  reduced  to  mul- 
tiples of  the  variabilities  in  question)  any  given  divergence  in  the 
one  trait  would  imply,  on  the  average,  62  hundredths  as  much  di- 
vergence in  the  other. 

Samples  of  the  Interrelations  of  Mental  Traits 

As  samples  of  R's  so  calculated  I  give  in  Table  20  some  of 
those  obtained  by  Burt  ['09]  in  the  case  of  30  boys  between  12^ 
and  133^  years  of  age  in  an  Elementary  School  in  Oxford,  at- 
tended by  boys  '  of  the  lower  middle  class  ',  whose  parents  paid 
9d.  a  week  tuition.  The  relations  are  all  between  divergences, 
each  from  the  central  tendency  of  the  group  in  the  trait  in  ques- 
tion.   The  traits  were  (in  part)  : — 

Touch. — Delicacy  of  simultaneous  discrimination  of  two  points  on  the  skin. 

Weight. — Delicacy  of   discrimination   of  lifted  weights. 

Pitch. — Delicacy  of  discrimination  of  pitches  (from  320  vibs.)  . 

Length. — Delicacy  of  discrimination  of  length;  deviation  from  the 
standard,  100  mm. 

Tapping. — The  number  of  holes  made  in  15  sec.  in  a  sheet  of  paper  over 
cloth,  a  needle  fastened  in  a  holder  being  used. 

Dealing. — The  time  required  to  deal  50  cards  into  5  heaps  in  the  ordinary 
manner. 

Sorting. — The  time  required  to  deal  50  cards  into  5  heaps  in  accordance 
with  the  color  of  the  cards.  An  error  was  not  corrected  by 
the  boy,  but  was  allowed  for  by  an  addition  to  his  time- score. 


1 82  Educational  Psychology 

Alphabet  Sorting. — 52  cards,  each  20  mm.  square  and  printed  with  a  letter, 
each  letter  appearing  twice  in  the  series,  were  exposed  in  an 
irregular  order.  The  boy  was  required  to  find  a,  then  to  find 
b,  then  c,  etc.,  placing  them  in  order  in  two  rows.  He  then 
repeated  this  selecting  again.     The  time  taken  was  the  score. 

Immediate  Memory. — Of  90  words  (30  concrete,  30  abstract,  and  30  non- 
sense) all  of  one  syllable,  each  one  seen  and  pronounced  by 
the  boy,  given  in  series  of  4,  5,  6,  7,  or  8.  For  method  of 
scoring  see  Burt,  '09,  p.   142. 

TABLE  20. 

The  Interrelations  of  Nine  Mental  Traits  in  the  Case  op  Thirty  Boys 

Each  Entry  Gives  the  Relation  of  the  Trait  Listed  on  the 

Line  to  the  Left  of  the  Entry  to  the  Trait  Listed 

Above  the  Entry.     Adapted  from  Burt  fog]. 

Decimal  Points  are  Omitted. 

4-1 

bo         ja  t^ 

a  ed  o 

V.      -5       a 


A 

^ 

bo 

a 

bo 

0 

bo 

JS 

bo 

'S. 

*y^ 

3 

■3 

0 

C 

o< 

S 

0 

^ 

s 

^ 

0) 

p 

cu 


m 


Touch                                    37  — 01  26  12  32  20  66  15 

Weight                       37  06  — 16  II  05  23  26  07 

Pitch  — 01         06  — 05  53  41  25  68  19 

Length                        26  — 16  — 05  16  59  32  37  05 


Tapping 

12 

II 

53 

16 

79 

78 

67 

01 

Dealing 

32 

05 

41 

59 

79 

77 

83 

18 

Sorting 

20 

23 

25 

32 

78 

77 

83 

27 

Alphabet 

66 

26 

68 

37 

67 

83 

83 

47 

Memory 

15 

07 

19 

05 

01 

18 

27 

47 

The  figures  of  Table  20  show  the  traits  measured  by  the  tap- 
ping, dealing  and  sorting  tests  to  be  so  related  that  the  amount 
of  any  one  possessed  by  a  boy  gives  a  fairly  close  prophecy  of 
the  amounts  that  he  will  possess  of  the  others.  The  traits  meas- 
ured by  the  tests  of  discrimination  of  touches,  weights,  pitches 
and  lengths  on  the  other  hand  are  shown  to  be  highly  independent 
one  of  another. 

Mental  relations  have  been  measured  by  Wissler  ['01],  Spear- 
man ['04a,  '04b,  '06],  Thorndike  ['03,  '09],  Pearson  ['07], 
Brown  ['09],  Burt  ['09],  Frost,*  Simpson,*  and  others.  The 
results  form  a  body  of  facts  of  great  importance  to  psychology 
and  education,  but  a  summary  of  them  without  elaborate  discus- 
sion of  the  methods  used  in  each  case,  would  be  misleading.     I 

*In  a  study  as  yet  unpublished. 


Relations  Between  Mental  Traits  183 

shall,  therefore,  state  only  the  general  conclusions   to  which  they 
lead. 

The  Significance  of  the  Relations  Between  the  Amounts  of 
Different  Traits  in  the  Same  Individual 

The  significance  of  the  relations  between  mental  traits  which 
have  been  measured  in  this  way  is  seen  most  easily  and  clearly 
by  observing  the  doctrines  about  individual  psychology  which 
they  disprove. 

First  may  be  mentioned  a  series  of  beliefs  in  mental  antago- 
nisms or  compensations.  Such  are : — that  superiority  to  the  cen- 
tral tendency  in  vividness  and  fidelity  of  imagery  of  one  sort 
implies  inferiority  to  the  central  tendency  in  vividness  and  fidelity 
of  imagery  of  other  sorts ;  that  superior  ability  to  get  impres- 
sions through  one  sense  is  related  to  inferiority  in  getting  im- 
pressions through  other  senses ;  that  intensity  of  attention  varies 
amongst  individuals  in  opposition  to  breadth  of  attention,  so  that 
a  high  degree  of  power  to  attend  to  one  thing  at  a  time  goes  with 
a  low  degree  of  power  to  attend  to  many  things  at  once ;  that  the 
quick  learner  is  the  poor  rememberer ;  that  the  man  of  great  artis- 
tic gifts,  as  in  music,  painting  or  literary  creativeness,  is  weak 
in  scientific  ability  or  matter-of-fact  wisdom ;  that  divergence 
above  the  mode  in  power  of  abstract  thought  goes  with  diver- 
gence below  the  mode  in  thought  about  concrete  things ;  that 
the  man  of  superior  intellect  is  likely  to  be  of  inferior  mental 
health ;  that  the  rapid  worker  is  inaccurate ;  that  an  agile  mind 
goes  with  a  clumsy  body ;  etc.,  etc. 

Not  all  of  these  and  other  supposed  antagonisms  or  inverse 
relations  have  been  specifically  tested  by  the  calculation  of  the 
appropriate  R's ;  but  those  which  have  been  so  tested  have  been 
found  in  gross  error.  Betts  ['09]  found  the  R's  for  any  one  sort 
of  non-verbal  imagery  with  any  other,  in  respect  to  vividness, 
completeness  and  detail,  to  be  not  only  positive  but  high.  Peder- 
sen's  data  ['05]  show,  though  he  apparently  did  not  notice  the 
fact,  a  very  close  correlation  between  ability  to  grasp  presenta- 
tions through  the  eye  and  ability  to  grasp  presentations  through 
the  ear.  Meumann  ['07]  somewhat  grudgingly  admits  that  his 
contrast  between  "  men  with  typically  concentrative  or  intensive 
attention "  and  "  individuals  with  typically  distributive  atten- 
tion "  ['07,  vol.  I,  p.  500],  does  not  mean  that  the  person  who  is 


184  Educational  Psychology 

superior  in  the  one  is  inferior  in  the  other ;  that,  on  the  contrary, 
he  is  more  likely  to  be  superior  in  the  other  also  ("  je  grosser  die 
Konzentrationsfahigkeit  eines  Menschen,  desto  grosser  seine 
Distributionsfahigkeit "  ['07,  vol.  I,  p.  502  f.])  The  author 
['08]  has  shown  that  the  individuals  who  learn  a  thousand  words, 
as  in  a  vocabulary,  more  quickly  than  the  modal  man,  also,  in  a 
majority  of  cases,  remember  more  of  them  after  40  days.  Cattell 
['03]  finds  that  eminence  in  artistic  lines  implies  superiority  in 
politics  or  generalship  or  science  more  often  than  the  reverse. 
All  relevant  measurements  witness  to  a  positive  correlation  be- 
tween efficiency  in  thought  with  abstract  data  and  efficiency  in 
thought  with  concrete  data ;  also  between  the  ability  to  work  with 
greater  speed  at  a  given  accuracy,  and  the  ability  to  work  with 
greater  accuracy  at  a  given  speed.  Indeed  the  individual  who 
works  at  higher  speed  often  works  more  accurately  at  even  that 
higher  rate  than  does  the  slower  worker  at  his  more  favorable 
rate. 

The  relations  which  do  seem  to  be  inverse  are  very  instructive. 
They  are  mostly  cases  of  the  relation  of  a  desirable  divergence 
in  one  trait  to  an  undesirable  divergence  in  the  other.  Thus 
general  intellect  seems  to  be  antagonistic  to  sullenness.  Intellectual 
efficiency  seems  to  be  antagonistic  to  emotionality  in  the  crude 
sense. 

It  is  very,  very  hard  to  find  any  case  of  a  negative  correlation 
between  desirable  mental  functions.  Divergence  toward  what  we 
vaguely  call  better  adaptation  to  the  world  in  any  respect  seems 
to  be  positively  related  to  better  adaptation  in  all  or  nearly  all 
respects.  And  this  seems  specially  true  of  the  relations  between 
original  capacities. 

The  negative  values  in  Burt's  results,  listed  above,  are  probably 
not  exceptions  to  this  rule,  but  are  due  to  the  chance  variations 
from  truth  which  are  to  be  expected  from  a  small  series  of 
measures.  His  -.16  for  the  relation  of  discrimination  of  length 
to  discrimination  of  weight,  for  instance,  should  be  considered  in 
connection  with  the  +.52  obtained  by  the  author  ['09]  for  the 
same  relation  in  the  case  of  37  young  women,  and  the  +.25 
obtained  in  the  case  of  25  high  school  boys. 

There  may,  however,  be  cases  where  some  one  large  environ- 
mental agency  acts  to  bring  all  those  individuals  subject  to  it  up  in 
one  trait  but  down  in  another.       The  Roman  Catholic  Church 


Relations  Between  Mental  Traits  185 

might  thus,  at  least  at  certain  periods  of  its  history,  make  many 
of  its  members  more  interested  in  theological  argumentation,  and 
less  interested  in  scientific  verification,  than  the  modal  man.  The 
theory  of  asceticism  might  make  all  its  adherents  successful  in 
contemplation  and  inefficient  in  action.  City  life  might  so  stimulate 
adroitness  in  dealing  with  people  and  inhibit  adroitness  in  dealing 
with  animals  and  plants,  as  to  produce  a  negative  relation. 
Wherever  some  potent  circumstances  act  to  elevate  dne  trait  and 
depress  another  in  individuals  subjected  to  them,  whereas  alterna- 
tive circumstances  act  in  the  opposite  direction,  there  is  a  chance 
for  individuals  to  show  negative  R's  in  the  traits  in  question, 
even  though,  in  original  nature,  the  traits  are  related  positively. 
Such  negative  relations  might  appear,  if  men  were  measured  from 
different  national  cultures  or  over  thousands  of  years  so  as  to 
include  such  contrasting  environments,  in  cases  where  our  present 
measurements  show  even  strong  positive  relations. 

Little  is  known  about  the  shares  of  original  mental  organization 
and  environmental  influences  in  producing  the  relations  of  diver- 
gence in  one  trait  to  divergence  in  others,  and  still  less  about  the 
special  efifect  of  what  may  be  called  irrational  environments,  those 
which  weaken  or  inhibit  certain  generally  desirable  mental  traits. 

Finally,  there  are  the  notable  cases  of  apparent  compensation 
due  to  the  special  practice  of  one  trait  to  make  up  for  irremediable 
weakness  in  some  other.  Keenness  of  touch  in  the  blind,  is,  of 
course,  the  clearest  case.  Of  such  cases  it  may  be  said  that  they  are, 
for  the  general  relation,  trifles,  and  are  partly  balanced  by  other 
cases  where  special  defect  and  special  practice  work  to  the  opposite 
effect  upon  the  total  relation.  It  should  also  be  noted  that  in 
original  nature  the  rule  is  correlation,  not  compensation.  Those 
defective  in  vision  are,  by  nature  alone,  more  likely  to  be  defective 
in  other  senses  than  are  those  superior  in  vision. 

On  the  whole,  negative  correlations  between  different  'efficiencies' 
or  '  adaptabilities  '  or  '  desirable  traits  '  are  surely  rare,  seem  almost 
never  to  occur  as  a  result  of  original  mental  nature,  and  require 
as  causes  peculiar  oppositions  of  influence  upon  the  two  traits  from 
the  environment. 

A  second  error  in  opinions  about  mental  relations  is  in  sharp 
contrast  to  the  one  just  described.  It  is  the  doctrine  that  some 
one  function  is  shared  by  all  intellectual  traits,  and  that  whatever 
resemblances  or  positive  correlations  the  traits  show  are  due  to 


i86  Educational  Psychology 

the  presence  in  each  of  them  of  this  function  as  a  common  factor. 
In  so  far  as  they  have  it,  they  are  identical.  In  so  far  as  they 
lack  it,  they  are  totally  disparate.  In  the  words  of  Spearman 
['04  b,  p.  84],  who  advocates  such  a  view,  "All  branches  of  intellec- 
tual activity  have  in  common  one  fundamental  function  (or  group 
of  functions)  whereas  the  remaining-  or  specific  elements  of  the 
activity  seem  in  every  case  to  be  wholly  different  from  that  in 
all  the  others." 

This  doctrine  requires  not  only  that  all  branches  of  intellectual 
activity  be  positively  correlated,  which  is  substantially  true,  but 
also  that  they  be  bound  to  each  other  in  all  cases  by  one  common 
factor,  which  is  false.  The  latter  would  require  that  no  two 
intellectual  abilities  or  branches  of  intellectual  activity  should  be 
more  closely  related  to  each  other  than  to  the  fundamental  func- 
tion by  which  alone  they  are  supposed  to  be  related ;  and,  as  a 
corollary  of  this,  that  no  four  such  abilities,  A,  B,C,andD,  should 
be  more  closely  related  in  pairs,  A  to  B,  and  C  to  D,  than  the 
element  common  to  A  and  B  is  related  to  the  element  common 
to  C  and  D.  But  unless  one  arbitrarily  limits  the  meaning  of  '  all 
branches  of  intellectual  activity  '  so  as  to  exclude  a  majority  of 
those  so  far  tested,  one  finds  traits  closely  related  to  each  other 
but  with,  their  common  element  only  loosely  related  to  the  common 
element  of  some  other  pair. 

The  next  error  may  be  roughly  described  as  the  supposition  that 
for  any  one  operation  that  is  the  same  in  form,  such  as  discrimina- 
tion of  differences,  attention,  observation,  inference  or  the  like, 
the  varieties  produced  by  different  data  or  content  are  perfectly 
correlated. 

It  has  been  common  in  psychological  and  educational  literature 
to  presuppose  that  the  functions  which  we  group  under  the  same 
name,  e.  g.,  attentiveness,  somehow  implied  each  other,  that,  for 
instance,  a  high  status  in  attentiveness  to  school  work  was  closely 
related  to  a  high  status  in  attentiveness  to  social  duties,  business 
pursuits,  mechanical  appliances  and  all  the  other  facts  of  the 
individual's  experience.  Our  rough  and  ready  descriptive  words, 
such  as  accuracy,  thoroughness,  reasoning  power  and  concentration, 
have  been  used  as  if  the  quality  must  be  present  in  approximately 
equal  amounts  in  all  the  different  spheres  of  mental  activity. 
The  notion  of  any  special  mental  act,  e.  g.,  the  discrimination  of 
100  millimeters  from  104,  has  apparently  been  that  some  general 


Relations  Between  Mental  Traits  187 

faculty  or  function,  discrimination,  was  the  main  component,  the 
special  circumstances  of  that  particular  act  being  very  minor 
accessories.  Thus  all  the  different  acts  in  the  case  of  discrimination 
would  be  very  closely  related  through  the  presence  in  them  a'l  of 
this  same  mental  component. 

On  the  contrary,  measurements  reveal  a  high  degree  of 
independence  of  different  mental  functions  even  where  to  the 
abstract  psychological  thinker  they  have  seemed  nearly  identical. 
There  are  no  few  elemental  '  faculties  '  or  forms  of  mental  activity 
which  work  alike  with  any  and  every  kind  of  content. 

For  instance,  the  correlation  in  adults  between  ( i )  memory  for 
figures  and  (2)  memory  for  unrelated  words  (memory  being 
used  to  mean  the  power  to  keep  a  list  in  mind,  after  once  hearing 
it,  long  enough  to  write  it  down)  is  not  over  .8;  the  correlation  in 
pupils  of  the  highest  grammar  grade  between  (i)  quickness  in 
thinking  of  the  opposites  of  words  and  of  the  letters  preceding 
given  letters  of  the  alphabet  and  (2)  quickness  in  thinking  of  the 
sums  of  figures  is  not  over  .7.  Yet  the  first  pair  of  tests  would 
commonly  be  used  indiscriminately  as  tests  of  '  memory,'  and  the 
second  pair  as  tests  of  '  association.'  upon  the  supposition  that  the 
two  members  of  each  pair  were  practically  identical  traits.  Even 
so  apparently  trivial  a  difference  as  that  between  drawing  a  line 
to  equal  a  100  mm.  line  and  drawing  a  line  to  equal  a  50  mm.  line 
causes  a  reduction  from  perfect  correlation.  The  resemblance  is, 
for  37  young  women  students,  only  .yy. 

A  table  of  the  known  degrees  of  relationship  would  abundantly 
confirm  the  statement  that  the  mind  must  be  regarded  not  as  a 
functional  unit,  nor  even  as  a  collection  of  a  few  general  faculties 
which  work  irrespective  of  particular  material,  but  rather  as  a 
multitude  of  functions  each  of  which  involves  content  as  well  as 
form,  and  so  is  related  closely  to  only  a  few  of  its  fellows,  to  the 
others  with  greater  and  greater  degrees  of  remoteness. 

The  mental  sciences  should  at  once  rid  themselves  of  the  con- 
ception of  the  mind  as  a  sort  of  machine,  different  parts  of  which 
sense,  perceive,  discriminate,  imagine,  remember,  conceive,  asso- 
ciate, reason  about,  desire,  choose,  form  habits,  attend  to.  Such 
a  conception  was  adapted  to  the  uses  of  writers  of  books  on  gen- 
eral method  and  arguments  for  formal  discipline  and  barren  de- 
scriptive psychologies,  but  such  a  mind  nowhere  exists.  There 
is  no  one  power  of  sense  discrimination  to  be  delicate  or  coarse. 


i88  Educational  Psychology 

no  capacity  for  uniform  accuracy  in  judging  the  physical  stimuli 
of  the  outside  world.  There  are  only  the  connections  between 
sense-stimuli  and  our  separate  sensations  and  judgments  thereof, 
some  resulting  in  dehcate  judgments  of  difference,  some 
resulting  in  coarse  judgments.  There  is  no  one  memory 
to  hold  in  a  uniformly  tight  or  loose  grip  all  the  experiences  of  the 
past.  There  are  only  the  particular  connections  between  particu- 
lar mental  events  and  others,  sometimes  resulting  in  great  surety 
of  revival,  sometimes  in  little.  And  so  on  through  the  list.  Good 
reasoning  power  is  but  a  general  name  for  a  host  of  particular 
capacities  and  incapacities,  the  general  average  of  which  seems 
to  the  namer  to  be  above  the  general  average  in  other  individuals. 
Modern  psychology  has  sloughed  off  the  faculty  psychology  in  its 
descriptions  and  analyses  of  mental  life,  but  unfortunately  reverts 
customarily  to  it  when  dealing  with  dynamic  or  functional  rela- 
tionships. 

But  it  is  just  in  the  questions  of  mental  dynamics  and  of  the 
relationships  of  mental  traits  that  we  need  to  bear  in  mind  the 
singularity  and  relative  independence  of  every  mental  process,  the 
thoroughgoing  specialization  of  the  mind.  The  mind  is  really 
but  the  sum  total  of  an  individual's  feelings  and  acts,  of  the  con- 
nections between  outside  events  and  his  responses  thereto,  and  of 
the  possibilities  of  having  such  feelings,  acts  and  connections.  It 
is  only  for  convenience  that  we  call  one  man  more  learned  than 
another  instead  of  giving  concrete  lists  of  the  information  pos- 
sessed by  each  and  striking  averages  from  all  the  particulars ; 
that  we  call  one  man  more  rational  than  another  instead  of  com- 
paring two  series  of  rational  performances.  In  any  one  field  the 
comparison  may  give  a  result  widely  different  from  the  general 
average.  So  also  with  inhibition,  concentration,  or  any  other  of 
the  general  names  for  forms  of  mental  action. 

It  is  easier  to  show  that  mental  traits  are  not  related  in  certain 
ways  than  it  is  to  show  directly  just  how  they  are  related.  There 
are  three  reasons  for  this.  The  first  is  that,  until  the  work  of 
Spearman  in  1904,  it  was  not  known  that  any  relation,  calculated 
from  other  than  complete  measurements  of  the  divergences  to  be 
related,  would  be  reduced  from  its  true  amount  toward  o.  Wissler, 
for  example,  found  ['01]  the  relation  between  accuracy  in 
drawing  a  line  to  equal  a  100  mm.  line  and  accuracy  in  bisecting 
it,  to  be  only  ,38,  because  he  had  as  measures  of  the  two  traits  to 


Relations  Between  Mental  Traits  189 

be  related  only  the  results  with  a  single  line.  If  each  individual 
had  been  tested  with  hundreds  of  lines  at  different  times  so  as 
to  get  his  real  total  abilities  the  result  would  have  been  an  R  of 
.7  or  .8.  Since  this  fact  of  the  '  attenuation '  of  the  R's  obtained 
from  imperfect  original  data  was  not  realized  at  all  until  1904, 
and  is  not  realized  by  many  students  even  now,  the  majority  of 
the  R's  that  have  been  calculated  are  of  doubtful  meaning.  For 
only  very  rarely  have  the  measurements  of  individuals  in  any 
trait  included  many  tests  on  many  dates  under  many  circum- 
stances so  as  to  give  adequate  measures.  The  true  R's  can  only  be 
inferred  from  the  obtained  R's  by  a  guess  at  the  degree  to  which 
the  latter  are  attenuated.  In  the  case  just  quoted  the  true  R  turns 
out  twice  the  obtained ;  in  other  cases  it  turns  out  to  be  only  a 
trifle  greater,  depending  of  course  on  the  chance  deviations  of 
the  original  measures. 

The  second  reason  for  our  inability  to  give  a  clear,  simple, 
positive  account  of  the  relations  of  mental  divergences  is  that  the 
divergences  related  have  been  measured  in  different  groups  and 
from  all  sorts  of  different  central  tendencies.  The  result  is  that 
many  of  the  relations  known  are  not  directly  comparable.  For 
example  R  for  general  scholarship  with  quality  of  handwriting  is, 
in  children  in  the  elementary  school,  being  measured  by  their 
divergences  from  the  central  tendencies  of  their  age  and  sex, 
about  .3.  R  for  general  scholarship  and  desultory  memory  is, 
certain  educated  adults  being  measured  by  their  divergences  from 
the  central  tendencies  of  graduate  students,  also  about  .3.  But 
the  two  relations  are  really  not  equal. 

The  third  reason  is  that  the  fact  itself  would,  in  any  case,  be 
too  complex  for  clear  and  simple  positive  description.  The  facts 
which  we  do  know  prove  that  if  we  knew  all  the  facts  the  inter- 
relations of  mental  traits  would  be  irreducible  to  any  easy  repre- 
sentation.   This  is  itself,  however,  an  important  fact  about  them. 

Such  a  general  positive  description  as  can  be  given  will  be 
best  given  in  graphic  form.  Let  the  series  of  horizontal  lines  in 
Fig  63  be  each  a  scale  for  some  mental  trait ;  let  the  right  end 
always  represent  superiority  in  the  trait ;  let  the  central  tendency 
of  adult  human  beings  be  in  each  case  at  the  point  on  the  scale 
where  a  vertical  line  down  the  center  of  the  diagram  would  cut 
the  scale.  The  C.  T.'s  for  all  traits  are  then  in  a  vertical  line. 
Let  a  constant  distance  always  equal  the  variability  of  the  trait. 


igo  Educational  Psychology 

Let  any  one  individual  be  represented  by  a  line  joining  all  the 
points  denoting  each  his  ability  in  one  trait.  Five  individuals 
are  thus  represented  in  Fig.  63,  in  ten  traits.  If  now,  instead  of 
ten  horizontal  scales  for  the  traits,  there  were  the  thousands 
necessary  to  inventory  human  faculty,  and  if,  instead  of  five 
cross-lines  for  five  individuals,  we  had  thousands  representing  a 
fair  sampling  of  all  men,  the  picture  would  show  a  rough  general 
parallelism  of  the  cross-lines  corresponding  to  the  general  tend- 
ency for  efficiency  in  one  trait  to  go  with  efficiency  in  others. 
There  would  be  very  few  cross-lines  from  the  extreme  left  of 


Fig.  63.  Ten  traits  shown  in  their  interrelations  in  the  case  of  each 
of  five  individuals.  Three  of  the  individuals  are  university  teachers  or 
graduate  students.     The  other  two  are  inferior  day-laborers. 

one  scale  to  the  extreme  right  of  the  other.  On  the  other  hand 
there  would  be  few  horizontal  lines  cut  by  the  same  man's  cross- 
lines  at  the  same  distances  from  the  C.  T.  There  would  be  many 
cross-lines  that  departed  from  the  general  drift  of  the  cross-lines 
a  little ;  some  that  departed  from  it  more ;  and  a  few  that  departed 
from  it  enormously. 

The  first  impression  would  be  of  a  general  parallelism,  i.e., 
perpendicularity,  of  the  cross-lines  disturbed  at  haphazard,  some- 
what as  geological  strata  are  distorted  from  their  parallelism  in 
a  mountain  region.  If,  however,  one  examined  the  relations,  he 
would  find  certain  rough  rules  for  prophesying  others.  Rela- 
tions would  in  general  be  closer  within  the  analytical  or  abstract- 


Relations  Betzveen  Mental  Traits  191 

ing  functions  than  between  these  and  others.  So  also  within  the 
purely  mental  associative  functions  like  adding,  completing  words, 
giving  opposites,  and  naming  objects,  than  between  one  of  them  and 
one  of  the  sensori-motor  functions.  The  sensitivities  would  inter- 
relate only  loosely  ;  and  any  one  of  them  would  relate  very  loosely 
to  the  associative  or  analytical  functions,  even  when  busied  with 
data  from  that  sense.  Sensitivity,  association,  and  analysis  would 
justify  their  claims  to  the  title  of  fundamental  forms  of  mental 
life,  by  showing  closer  intra-  than  inter-relations.  The  association 
of  sense  impressions  with  movement,  the  association  of  percepts 
and  images  as  such  with  one  another  and  with  movement,  and 
the  association  of  symbols  or  meaning-carriers  such  as  percepts 
and  images  of  words,  would  be  found  to  deserve  recognition  as 
three  '  levels  '  of  mental  action  for  the  same  reason.  Certain 
functions  quite  diverse  from  the  point  of  view  of  the  fundamental 
forms  of  mental  life  or  the  '  levels  '  of  the  associative  form  would 
be  found  to  be  related  by  reason  of  some  instinctive  tendency. 
Different  degrees  of  the  instinctive  interest  in  persons  might  thus 
produce  correlations  between  love  of  ceremonies,  ability  in  sociol- 
ogy and  interest  in  literature.  The  variations  in  the  love  of  mental 
activity  are  one  root  of  many  of  the  correlations  between  all  sorts 
of  efficiencies. 

In  more  detail,  the  scale  for  any  ability  would  be  cut  by  a 
cross-line  at  about  the  same  point  that  this  cross-line  cut  the  scale 
for  the  corresponding  interest ;  the  scales  for  sensory  and  sensori- 
motor powers  would  be  cut  by  cross-lines  in  only  a  loose  cor- 
respondence with  the  scales  for  ideational  controls ;  a  cross-line 
would  go  far  to  the  right  or  left  as  it  passed  from  an  ability  to 
analyze  out  intellectual  elements  to  an  ability  to  make  a  precise 
movement.  But  the  great  majority  of  the  details  would  be  blurred 
in  the  picture  by  our  lack  of  knowledge. 

Finally  the  circumstances  of  training  would  be  seen  to  some- 
times intensify  and  sometimes  weaken  original  relations.  Thus 
the  variations  in  the  length  of  school  training,  by  connecting  a 
long  training  in  certain  traits  almost  inevitably  with  a  long  train- 
ing in  certain  other  traits,  make  certain  correlations  more  pro- 
nounced. The  world  over,  there  is  a  close  relation  between  knowl- 
edge of  Latin  and  knowledge  of  geometry,  far  beyond  what  nat- 
ural interests  would  produce. 


192  Educational  Psychology 

A  case  of  the  weakening  of  an  original  relation  by  training 
might  be  furnished  by  ability  in  mathematics  and  ability  in  under- 
standing human  nature.  The  original  relation  is  perhaps  closer 
than  the  actual  relation  in  adults,  the  common  forms  of  training 
tending  so  often  to  develop  one  or  the  other. 

Roughly  the  effect  of  the  environment  is  to  make  closer  the 
relations  due  to  content.  A  mother  comes  to  observe,  attend  to, 
and  remember  her  children  well ;  the  plumber  '  develops  all  his 
powers  ',  as  the  educational  theorists  were  fond  of  saying,  so  far 
as  plumbing  goes,  and  neglects  them  beyond  that  point ;  the 
classical  student  takes  a  high  position  in  every  formal  operation 
when  Latin  is  the  datum  operated  on. 

Just  what  the  original  relations  are  will  in  the  progress  of  re- 
search be  discovered.  It  is  unlikely  that  the  relations  of  original 
capacities  and  instincts,  including  native  interests,  are  so  compli- 
cated as  the  relations  amongst  adult  achievements  and  abilities. 
But  present  knowledge  is  insufficient  to  determine  even  the  orig- 
inal relations. 


CHAPTER  X 

The  Nature  and  Amount  of  Individual  Differences  in 

Combinations  of  Traits  :  Types  of  Intellect 

AND  Character 

Scientific  studies  of  the  natures  of  individual  men  in  combina- 
tions of  traits  by  the  direct  method  have  been  very  few  and 
very  inadequate  in  respect  to  both  the  number  of  individuals  and 
the  number  of  traits  studied.  The  measurements  of  mental  rela- 
tions described  in  the  last  chapter  are  the  main  means  of  improv- 
ing upon  common  opinion  concerning  the  varieties  of  human 
nature  in  respect  to  total  make-up,  or  to  such  large  fractions  of 
it  as  are  roughly  denoted  by  temperament,  mode  of  thought, 
morals,  mental  health,  manner  of  work,  imagination,  and  the 
like. 

A  Sample  Problem:  Individual  Differences  in  Imagery 

As  a  sample  of  the  problems  and  their  treatment  we  may  take 
the  natures  of  individuals  in  respect  to  type  of  imagery,  that  is, 
in  respect  to  the  combination  of: — vividness  of  visual  images, 
fidelity  of  visual  images,  frequency  of  visual  images,  vividness 
of  auditory  images,  fidelity  of  auditory  images,  and  so  on,  through 
the  list. 

Early  in  the  history  of  the  scientific  study  of  imagery  it  was 
noted  that  certain  individuals  were  able  to  recall  in  memory  pres- 
entations to  one  sense  with  a  high  degree  of  vividness  and  fidelity, 
but  lacked  this  power  in  the  case  of  presentations  to  some  other 
sense.  The  existence  of  persons  who,  for  instance,  could  get 
before  the  mind's  eye  vividly  and  with  full  detail  a  mental  photo- 
graph, as  it  were,  of  a  scene,  but  could  not  thus  reproduce  from 
within  a  melody,  an  itching  nose,  or  a  blow,  naturally  gave  rise 
to  the  notion  of  the  '  visualizing  type.' 

Such  cases,  of  notable  ability  to  get  one  sort  of  images  and 
notable  inability  to  get  other  sorts,  were  then  carelessly  assumed 
to  be  the  rule.     It  was  supposed  that  a  high  degree  of  vividness, 

(193) 
13 


194 


Educational  Psychology 


fidelity  and  frequency  in  images  from  one  sense  tended  to  exclude 
an  equally  high  degree  in  images  from  other  senses.  People  were 
called  visualizers,  audiles,  motiles,  etc.,  with  the  meaning  that 
the  visualizers  had  more  vivid,  faithful  and  frequent  visual  images 
than  other  people  and  less  vivid,  faithful  and  frequent  images 
from  other  senses,  and  similarly  for  the  audiles,  or  motiles.  In 
graphic  form  this  view  would  give  Fig.  64. 

But  the  actual  examination  of  individuals  showed  such  ex- 
clusiveness  or  predominance  of  one  sort  of  imagery  to  be  the 
exception  rather  than  the  rule.  To  even  superficial  examination 
it  was  evident  that  human  natures  did  not  fit  into  the  scheme  of 
Fig.  64  at  all  well.  Even  those  who  believed  unhesitatingly  that 
human  natures  must  be  distributed  around  fairly  distinct  types 


T  — 


Fig.  64.  The  interrelations  of  the  degree  of  development  of  visual, 
auditory,  motor,  and  touch  imagery  according  to  the  theory  of  pure  types. 
Imaginary  horizontal  lines  at  V,  A,  M  and  T  are  scales  for  the  degree 
of  vividness,  fidelity  and  frequency  of  visual,  auditory,  motor  and  touch 
imagery  respectively.  The  lowest  degree  is  in  each  case  at  the  left.  12 
individuals  are  represented,  each  by  a  line  crossing  each  of  the  scales  at 
the  point  representing  the  individual's  abiHty. 

in  respect  to  imagery  could  not,  try  as  they  might,  distribute  in- 
dividuals around  these  types.  Meumann  in  fact  admits  that  in 
all  his  studies  of  children  he  never  found  one  such  pure  type. 
"  How  rare  the  pure  types  [of  imagery]  are  amongst  children 
is  witnessed  by  the  fact  that  in  our  extensive  investigations  of 
children  at  Zurich  we  have  never  found  a  perfectly  pure  type. 
Also  I  know  of  no  case  in  the  entire  literature  of  the  subject  in 
which  sure  proof  is  given  of  the  existence  of  a  pure  type  in  the 
case  of  children."  ['07,  I,  p.  494]  So  new  intermediate  types, 
such  as  the  auditory-motor,  visual-motor,  auditory-visual,  or  even 
visual-auditory-motor-intellectual    (!)    [Segal,   '08],   were   inlro- 


II 


Individual  Differences  in  Combinations  of  Traits         195 

duced.  There  the  matter  remained  until  Betts  ['09]  actually 
measured  a  sufficient  number  of  individuals  in  respect  to  the 
vividness  and  fidelity  of  non-verbal  images  from  the  different 
sense-fields,  so  that  the  cross-lines  of  Fig.  64  could  be  located  by 
fact  instead  of  by  opinion. 

The  pillars  of  the  doctrine  were  the  separation  of  men  into 
types  according  to  the  predominance  of  images  from  one  sense, 
and  the  existence  of  inverse  relations  between  the  different 
sense-spheres  in  respect  to  the  extent  and  perfection  of  imagery. 
Fact  showed  opinion  to  have  been  grossly  in  error  as  a  result 
of  its  assumption  that  distinct  types  of  some  sort  there  must  be. 
The  contrary  is  true.  Instead  of  distinct  types,  there  is  a  con- 
tinuous gradation.  Instead  of  a  few  '  pure '  types  or  many 
'  mixed '  types,  there  is  one  type — mediocrity.  Instead  of  antag- 
onism between  the  development  of  imagery  from  one  sense  and 
that  from  other  senses  there  is  a  close  correlation.  Fig.  65  is  a 
fair  sample  of  the  facts  found. 

This  case  is  instructive  because  the  fate  of  many  theories 
concerning  distinct  types  of  human  nature  in  combinations  of 
traits  is  likely  to  be  the  same  as  the  fate  of  the  doctrine  of  types 
of  imagery  according  to  the  sense  involved,  with  inverse  rela- 
tions between  the  development  of  imagery  from  one  sense-field 
and  that  from  other  fields.  In  the  case  of  temperament,  for 
example,  we  have  the  same  history.  Extreme  cases  are  given 
names  and  rriade  into  types.  Verbal  contrasts  are  supposed  to 
have  real  existence.  Supplementary  types  are  invented  to  help 
out  the  discrepancies  between  the  imagined  types  and  the  real 
distribution  of  individuals.  And  it  is  highly  probable  that,  when 
actual  measurements  are  made,  mediocrity — a  temperament 
moderately  sanguine,  choleric,  phlegmatic,  and  melancholy ;  mod- 
erately slow,  quick,  shallow,  intense,  narrow  and  broad ;  moder- 
ately slow-shallow,  slow-intense-narrow  ;  moderately  everything, — 
will  be  found  to  be  the  one  real  type. 

The  Theory  of  Multiple  Types  and  the  Single  Type  Theory 

The  sample  problem  shows  well  two  extreme  views  which  may 
be  taken  of  the  varieties  of  human  natures,  of  the  same  sex,  race 
and  degree  of  maturity,  in  respect  to  any  combination  of  traits. 
On  the  one  hand  is  the  theory  of  multiple  types,  a  theory  which 
separates  men  more  or  less  sharply  into  classes,  and  describes  a 


196 


Educational  Psychology 


man  by  naming  the  class  to  which  he  belongs.  On  the  other 
hand  is  the  theory  of  a  single  human  type,  a  theory  which  joins 
all  men  one  to  another  in  a  continuity  of  variation  and  describes  a 


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Indizndual  Differences  in  Combinations  of  Traits        197 

man  by  stating  the  nature  and  amount  of  his  divergences  from 
the  single  type. 

By  the  theory  of  a  single  type,  one  make-up  can  be  conceived 
such  that  from  it  all  individuals  would  differ  less  than  they 
would  from  any  other  one  make-up,  and  such  that,  the  greater 
the  divergences,  the  rarer  they  would  be.  By  the  theory  of  mul- 
tiple types,  no  such  single  true  central  tendency  would  exist.  By 
the  theory  of  multiple  types,  if  a  number,  K,  of  '  typical '  natures 
or  make-ups  are  most  favorably  taken  and  if  divergences  of  all 
individuals  are  measured  from,  in  each  case,  that  nature  which 
the  individual  most  resembles,  the  total  sum  of  divergences  is 
enormously  reduced  below  what  it  would  be  if  they  had  been 


Fig.  66.  A  graphic  representation  of  the  multiple-type  theory  in  the  case 
of  combinations  of  traits.  The  11  horizontal  dotted  lines  (drawn  only  at 
the  extremes)  represent  scales  for  11  traits.  Each  cross-line  represents, 
by  its  location,  the  amounts  of  the  11  traits  in  one  individual. 


measured  all  from  some  one  nature.  By  the  theory  of  a  single 
type,  this  reduction  in  the  sum  of  divergences  due  to  measuring 
each  individual's  divergence  from  any  one  of  K  natures,  is  much 
less. 

These  two  doctrines  can  be  made  clear  by  graphic  illustrations. 
Let  the  amount  of  each  trait  in  the  combination  be  scaled,  as  by 
our  custom,  horizontally,  the  center  always  representing  the  mode. 
Let  the  nature  or  make-up  of  each  individual  be  represented  by 
the  points  where  a  cross-line  denoting  him  cuts  the  scale  lines. 
The  theory  of  multiple  types  then  gives  something  like  Fig.  66, 


198 


Educational  Psychology 


and  that  of  one  type  something  like  Fig.  67.  All  the  cross-lines 
of  Fig.  66  can  be  represented  as  minor  divergences  from  five 
typical  cross-lines,  far  better  than  can  all  the  cross-lines  of  Fig. 
67.  Those  of  Fig.  6y  can  be  far  better  represented  by  one  typical 
cross-line  than  can  those  of  Fig.  66. 

A  radically  different  scheme  for  graphic  representation  will 
enable  the  reader  to  think  of  the  meaning  of  the  two  theories  for 
a  very  large  combination  of  traits,  say  total  mental  nature.  Sup- 
pose that  each  trait  is  scaled  into  5  amounts,  i,  2,  3,  4  and  5. 
Suppose  that  there  are  5  traits,  a,  b,  c,  d  and  e,  concerned  in  the 


Fig.  67.  A  graphic  representation  of  the  single-type  theory  in  the  case 
of  combinations  of  traits.  The  il  horizontal  lines  represent  scales  for  li 
traits.  Each  cross-line  represents  the  amounts  of  the  11  traits  in  one 
individual. 

total  complex.  Suppose  3  to  be  the  mode  in  each  trait.  Con- 
sider every  possible  cross-line,  every  possible  series  of  amounts 
in  the  5  traits  that  can  be  possessed  by  an  individual  (but  without 
fractionizing  any  scale  farther  than  into  fifths).  There  will  be 
3125  such  series  possible  (5  to  the  5th  power).  Now  suppose 
each  of  these  3125  series  of  amounts, — each  of  these  '  natures,' — 
to  be  represented  by  a  spot  of,  say,  .01  sq.  in.  on  a  surface. 
Suppose  further  that  the  center  spot  of  the  map  represents  the 
series  33333  (the  traits  being  now  and  later  always  taken  in 
order  a,  b,  c,  d  and  e).  Suppose  that  around  this  center  spot 
and  adjoining  it  are  placed  all  the  spots  or  areas  representing 
those  series  diverging  from  the  33333  series  by  only  one  unit, 
^•g-   23333,  43333.  32333.  etc.     Suppose  that  the  next  ring  is 


Individual  Differences  in  Combinations  of  Traits  199 

made  up  of  the  spots  or  areas  representing  those  series  diverging 
from  the  modal  series  by  two  units,  e.g.  22333,  43433,  53333, 
etc.  Continue  till,  in  the  outermost  ring,  we  have  areas  repre- 
senting the  series  55555,  iiiii,  11555,  51115,  etc.,  which  have 
the  greatest  possible  divergence  from  the  modal  series. 

Now  suppose  that  the  relative  frequencies  with  which  these 
series  appear  in  men  are  represented  each  by  the  height  of  a 
column  erected  with  the  appropriate  area  as  base.  Consider  the 
appearance  of  the  resulting  relief-map  according  to  the  two  the- 
ories. By  the  single  type  theory,  it  would  be  highest  over  some 
one  spot — in  our  illustration,  over  the  center  or  33333  spot.* 
By  the  multiple  type  theory,  it  would  have  several  maxima  over 
several  spots.  By  the  single  type  theory,  the  average  height 
would  be  less  and  less  over  each  successively  more  distant  con- 
centric ring.  The  whole  relief  map  would  look  like  a  mountain, 
with,  possibly,  many  radiating  and  cross  ridges,  casual  valleys 
and  eminences,  but  with,  always,  a  decreasing  elevation,  the 
larger  the  radius  of  a  circle  drawn  about  the  summit.  By  the 
multiple  type  theory,  the  average  elevation  need  bear  no  rela- 
tioii  to  the  distance  from  the  center  spot ;  the  depressions  would 
be  between  the  several  peaks  each  representing  a  type.  In  pro- 
portion as  the  types  were  held  to  be  very  sharply  distinct  and 
widely  separated,  these  intervalleys  would  be  deep,  even  to  the 
original  surface,  and  wide. 

Extend  now  the  process  of  construction  of  these  models  to 
thousands  of  traits  each  scaled  in  fifty  or  a  hundred  amounts,  and 
one  has  the  contrast  of  the  multiple  and  single  type  theories  applied 
to  men's  total  natures. 

It  is  not  necessary  to  try  to  decide  between  these  two  theories, 
or  to  determine  just  what  compromise  is  the  true  one.  It  is  bet- 
ter to  accept  frankly  our  ignorance  of  just  how  individuals  do 
differ  in  combinations  of  traits  until  they  have  been  measured 
in  respect  to  all  the  traits  involved. 

But  since,  in  general,  writers  about  human  nature  openly  or 
tacitly  assume  the  truth  of  the  multiple  type  theory  in  a  pro- 
nounced form,  and  are  governed  by  it  in  their  methods  of  re- 
search, of  interpretation  and  of  practical  control,  it  will  be  useful 

♦This  would  be  the  case  in  the  special  form  that  the  theory  would  almost 
certainly  take  in  the  case  of  combinations  of  5  traits,  each  unimodal,  with 
the  mode  at  mediocrity. 


200 


Educational  Psychology 


to  consider  briefly  some  of  the  arguments  in  favor  of  the  single 
type  theory. 

The  first  is  the  fact  that,  in  proportion  as  exact  measurements 
have  been  applied,  evidence  expected  to  favor  the  multiple  type 
theory  has  turned  out  in  favor  of  the  single  type  theory.  It  is 
true  that  such  cases  are  very  rare,  and  that,  until  they  are  much 
increased  in  number,  little  should  be  inferred  from  them.  But 
the  fact  remains  that  the  single  type  theory  arose  from  exact 
measurements,  while  its  opposite  came  from  speculative  pre- 
possessions. 

The  second  is  the  rarity  of  the  inverse  correlations  between 
desirable  traits  upon  which  so  many  of  the  supposed  multiple 


Fig.  68.  A  graphic  representation  of  the  condition  of  individuals  in  a 
combination  of  two  traits,  if  these  are  very  antagonistic  or  inversely 
correlated.    The  general  scheme  of  the  diagram  is  that  used  in  Figs.  63  to  67. 


Fig.  69.    A  graphic  representation  of  the  condition  of  individuals  in  a 
combination  of  two  traits,  if  these  are  closely  and  positively  related. 


types  are  based.  We  know  that  eye-minded  and  ear-minded, 
quick  and  careful,  broad  and  deep,  sensorial  and  intellectual,  men 
of  thought  and  men  of  action,  and  the  like  do  not  really  repre- 
sent human  nature's  varieties  in  the  combinations  referred  to. 
If  two  horizontal  scales  are  drawn  for  '  ability  to  learn  through 
the  eye  '  and  '  ability  to  learn  through  the  ear,'  and  the  cross- 
lines  are  drawn  for  a  thousand  individuals,  they  will  not  go  as 
in  Fig.  68  but  as  in  Fig.  69.  So  also  for  scales  for  quantity  of 
work  and  quality  of  work,  and  so  on  through  the  list. 


Individual  Differences  in  Combinations  of  Traits  201 

The  third  is  the  fact  that  the  single  traits  involved  are  so  often 
distributed  each  approximately  symmetrically  around  one  mode 
and  that  their  intercorrelations  are  so  often  approximately  recti- 
linear. In  so  far  as  such  is  the  case,  no  matter  what  the  closeness 
of  the  correlations  may  be,  the  distribution  of  the  individuals  in 
respect  to  the  combination  of  traits  will  be  around  one  mode  or 
peak  with  less  and  less  frequency  the  more  they  diverge  from 
that  mode.  The  mode  for  the  combination  will  be  a  nature 
which  is  at  the  mode  in  all  the  single  traits. 

The  fourth  is  the  fact  that  investigators  who  are  strongly  in 
favor  of  the  multiple  type  theory  and  accustomed  to  interpret 
facts  in  harmony  with  it,  yet  find  so  few  actual  cases  of  it. 
Meumann  for  instance  ['07,  vol.  I]  clearly  accepts  the  theory 
in  general  and  demands  that  educational  practice  should  give 
much  attention  to  the  classification  of  pupils  under  distinct  types. 
But  in  concrete  particulars  he  rarely  illustrates  it. 

He  says  ['07,  vol.  I,  pp.  331-332]  :  "  By  establishing  types  we 
orient  ourselves  in  the  endless  possibilities  of  individual  differ- 
ences, and  if  we  can  place  an  individual  under  a  type  .... 
in  any  respect  we  thereby  have  pointed  out  a  group  of  universal 
characters  in  his  mental  life,  which  he  in  general  shares  with 
some  individuals  and  by  which  he  is  in  general  distinguished 
from  others."  But  he  does  not  establish  such  types.  The  majority 
of  the  differences  which  he  does  report  as  '  typical '  are  differences 
between  two  extremes  of  the  same  trait.  Intermediate  conditions 
are  in  some  of  these  cases  demonstrably,  and  in  all  cases  probably, 
more  typical  than  the  supposed  types.  And  this,  indeed,  Meumann, 
in  some  cases,  admits. 

Lastly,  I  may  mention  the  fact  that  satisfactory  proof  of  the 
existence  of  a  distribution  of  human  individuals  after  the  fashion 
demanded  by  the  multiple  type  theory  has  never  been  given  in 
a  single  case,  and  that  the  evidence  offered  by  even  the  most 
scientific  of  the  theory's  adherents  is  such  as  they  would  cer- 
tainly themselves  consider  very  weak  if  they  were  not  already 
certain  that  types  of  some  sort  there  must  be.  Thus  a  fair- 
minded  perusal  of  Stem's  Psychologic  der  Indiznducllen  Differ- 
enzen,  designed  to  be  a  description  of  the  types  into  which  human 
nature  falls,  is  an  almost  sure  means  of  stimulating  a  shrewd 
student  to  the  suspicion  that  intermediate  conditions  are  more 
frequent  than  the  supposed  types,  and  that  there  are  far  more 


202  Educational  Psychology 

simply  ordinary  people  than  there  are  of  all  the  '  types '  put 
together.  I  report,  to  illustrate  this  point,  the  substance  of  all 
that  Stern  says  in  favor  of  the  multiple  type  theory  in  his  five 
chapters  on  Sensitivity,  Perception,  Memory,  Association  and 
Apprehension  ['oo,  pp.  40-77]. 

On  p.  43  f.  he  says,  "  We  know  the  enormous  gap  which  exists 
between  the  unmusical  and  the  musician  in  the  discrimination  of 
pitch,  between  the  perfumer  and  the  ordinary  person  in  the 
recognition  of  odors,  between  the  painter  and  the  book-worm 
in  the  delicacy  of  color  perception."  On  the  contrary, 
between  the  keenest  of  the  non-musical  and  the  dullest  of 
musicians  in  the  discrimination  of  pitch  there  is  no  enormous 
gap,  but  an  enormous  overlapping  (see  Spearman,  '04  b,  pp.  90 
and  92).  Stern  himself  later  points  out  that  a  little  special  prac- 
tice bridges  the  '  enormous  gap.' 

Stern  mentions  (p.  46)  "the  types  of  the  external  observer 
(the  experimental  scientist,  possibly)  and  of  the  introspective 
thinker  (the  mathematician  or  metaphysician,  possibly)."  But 
these  are  not  distinct,  contrasting  types.  The  experimental 
scientist  is  far  more  likely  to  be  a  good  mathematician  than  is  the 
ordinary  man.  Mathematical  ability  and  interest  are  in  no  sense 
confined  to  the  metaphysicians.  The  good  external  observer  may 
be  excellent  at  introspection,  and  the  man  with  a  strong  interest 
in  his  inner  life  of  thought  is  much  more  likely  than  the  average 
man  to  have  a  strong  interest  in  external  facts. 

Stern's  next  group  of  types  are  the  'Anschauungstypen.'  In- 
dividuals of  the  visual  type,  for  instance,  "  imagine  and  dream 
in  the  most  vivid  visual  images ;  they  notice  and  retain  colors, 
forms,  faces  with  especial  ease ;  they  reproduce  what  is  spoken 
predominantly  with  the  aid  of  images  of  the  printed  words ;  in 
fact  they  in  general  construct  their  world  of  ideas  in  great  meas- 
ure out  of  visual  elements."  The  more  such  extreme  develop- 
ment of  any  one  sense-sphere  exists  in  a  man,  the  more  "  the 
others  are  restricted  to  their  necessary,  indispensable  and  irre- 
placable  functions."  (p.  48)  But  here  again  the  facts  are  in 
opposition.  Such  cases  as  Stern  describes  are  extreme  and  very 
rare  divergences  from  common  mediocrity,  not  centers  near  which 
most  men  are  located. 

Stern  further  divides  men  into  a  '  formal '  and  a  '  material '  or 
'  content '  type  in  their  '  Anschauung '  or  mental  dealings  with 


Individual  Differences  in  Combinations  of  Traits  203 

concrete  objects.  The  formal  type  gets  the  rhythm  of  a  piece  of 
music  easily,  but  the  melody  only  with  difficulty.  The  '  content ' 
type  gets  the  melody  well,  but  the  rhythm  badly.  "The  former 
type  notices  and  retains  above  all  the  temporal  grouping  of  the 
sounds,  whose  qualitative  nature  and  relations  stay  far  in  the 
background.  With  the  latter  type,  on  the  contrary,  it  is  just  the 
material  of  the  sensations,  the  succession  of  different  pitches, 
which  is  made  the  instrument  of  musical  perception."  (p.  55) 
But  no  evidence  is  offered  of  this  supposed  inverse  correlation, 
and  all  that  is  known  of  the  relation  leads  to  the  expectation  that 
it  is  positive,  the  individual  best  at  getting  rhythm  being  better 
than  the  average  at  getting  melody  also. 

Stern  supposes  these  contrasting  types  to  exist  for  spatial  facts 
also.  Ability  with  position  and  outline  denotes  one  type ;  ability 
with  color,  light  and  shade,  another  type  (p.  57).  But  here 
again  the  supposed  inverse  relation  is  really  direct  The  supposed 
types  are  two  extreme  and  rare  divergences  from  the  real  single 
type,  an  individual  who  is  mediocrely  gifted  with  both  the  '  form ' 
and  the  '  material ',  with  both  line  and  color. 

In  the  case  of  memory.  Stern  reports,  not  multiple  types,  but 
gradations  from  single  types,  with  the  single  exception  that  he 
quotes  with  modified  approval,  "  Who  learns  easily,  forgets  eas- 
ily also ;  who  learns  with  difficulty,  retains  better."  This  is,  again, 
contrary  to  the  facts. 

Under  types  of  apprehension  or  apperception,  is  given  the 
classification  of  individuals  as  describers,  observers,  emotional, 
and  scholarly,  made  by  Binet  ['97]  on  the  basis  of  their  written 
descriptions  of  a  single  picture,  and  their  classification  as  describ- 
ers, observers,  imaginative  and  poetic,  and  scholarly,  made  (also 
by  Binet)  on  the  basis  of  written  descriptions  of  a  cigarette. 
Stern  points  out  that  much  more  elaborate  examinations  of  the 
children  are  necessary.  Leclere  ['98]  got,  in  a  single  experi- 
ment, seven  types,  which,  also,  are  not  at  all  distinct.  Of  course, 
many  samples  of  each  child's  '  apprehensions  '  or  '  apperceptions  ' 
of  objects  must  be  collected  and  classified  independently  by  many 
competent  psychologists,  and  the  exact  rating  of  each  person  on 
scales  for  scholarliness,  imaginativeness,  and  so  on  must  be  given, 
before  one  can  tell  whether  the  individuals  are  grouped  around 
one  type  or  around  several.    The  question  is  not  whether  Profes- 


204  Educational  Psychology 

sor  Binet  can  pick  out  certain  papers  that  are  distinctly  different, 
but  whether  the  common  judgment  of  experts  will  rank  the  indi- 
viduals in  classes  that  are  distinctly  different. 

The  above  is  all  that  is  given  as  evidence  for  the  multiple  type 
theory  in  the  first  35  pages  of  Stern's  inventory  of  types.  The 
balance  of  his  discussion,  devoted  to  Types  of  Attentiveness,  of 
Activity  in  Combining  Facts,  of  Judgment,  of  Reaction,  of  Feel- 
ing, of  the  Tempo  of  Mental  Life  and  of  Mental  Work,  would 
give,  if  anything,  less  satisfactory  evidence.  The  same  lack  would 
be  found  in  the  writings  of  Kraepelin,  Binet,  Meumann  and  their 
students. 

In  general  the  case  is  stronger  for  the  single  type  theory  in 
combinations  of  original  traits  than  in  traits  produced  by  train- 
ing. One  form  of  training — one  environment — may  possibly  pro- 
duce in  every  individual  who  is  subjected  to  it  certain  large 
increases  in  certain  mental  traits  and  certain  large  decreases  in 
others.  All  its  subjects  then  tend  thereby  to  differ  much  from 
all  other  men,  and  to  be  much  alike  among  themselves,  that  is,  to 
cluster  around  a  type  of  their  own.  Such  is  not  without  reason 
supposed  to  be  the  case  with  residence  in  a  given  nation,  frontier 
life,  city  versus  country  life,  household  industry  versus  factory 
industry,  slavery  versus  freedom,  and  the  like.  Just  as,  in  any 
one  trait,  the  action  of  disproportionately  large  factors  may  cause 
multimodality,  so,  in  any  combination  of  traits,  the  action  of  dis- 
proportionately large  factors  may  cause  multitypality.  And 
doubtless  there  would  appear  many  minor  eminences  upon  our 
relief-map  of  human  nature  due  to  the  influence  of  *  nation  lived 
in,'  '  language  spoken,'  *  occupation  followed,'  and  the  like.  The 
form  of  distribution  of  individuals  in  respect  to  combinations  of 
traits,  as  in  respect  to  single  traits,  is  a  secondary  result  of  the 
nature  and  interrelations  of  the  factors  that  produce  the  amounts 
of  the  traits.  There  is  no  mysterious  force  of  mental  life  herding 
all  individuals  of  the  same  sex,  age  and  race  around  mediocrity. 
Nor  is  there  such  a  force  separating  them  out  into  clusters 
around  distinct  types.  The  former  condition  certainly  occurs 
in  the  case  of  many  combinations  of  traits.  The  latter  may  very 
well  occur  in  the  case  of  others.  Knowledge  of  just  what  does 
occur  demands  objective  measurements  of  each  of  many  individ- 
uals in  each  of  the  traits  in  each  of  the  combinations  in  question. 


Individual  Differences  in  Combinations  of  Traits  205 

Individual  Differences  in  the  Average  Amount  of  a 
Combination   of  Traits 

There  are  many  combinations  of  traits  which  can  be  reduced  to 
single  traits  by  abstraction  from  some  of  their  particulars.  Sup- 
pose, for  example,  that  A  and  B  are  measured  in  respect  to 
efficiency  in  marking  A's,  in  marking  words  containing  each  the 
two  letters  a  and  t,  in  marking  hexagons  on  a  sheet  of  various 
simple  geometrical  forms,  in  marking  grays  of  a  certain  intensity 
on  a  sheet  with  200  squares  of  grays  of  five  intensities,  and  in 
marking  misspelled  words  on  a  sheet  containing  a  passage  with 
100  out  of  500  words  misspelled.  Suppose  the  results  to  be,  in 
terms  of  the  variability  for  each  trait : — 

A  B 

Marking  A's  -i.i  +1.0 

"       a-t  words  -1.4  +7. 

"       hexagons  -.6  +1.2 

"       grays  .0  -.2 

"       misspelled  words  -1.7  +1.4 

B- A  equals  2.1,  2.1,  1.8,  -.2  and  3.1  respectively. 

If  we  abstract  from  the  particular  differences  and  ask  only 
concerning  the  condition  of  A  and  B,  and  their  difference,  in 
average  efficiency  in  marking  these  five  sorts  of  visual  objects, 
the  result  is  that  A=  -.96  (-4.8  divided  by  5),  B=+.82 
(+4.1  divided  by  5)  and  B-A=  1.78. 

Such  abstraction  from  certain  particulars  of  each  of  a  combi- 
nation of  traits  can  be,  and  is,  in  both  ordinary  and  scientific 
thinking,  carried  so  far  as  to  unite  in  a  single  trait  very  diverse 
features  of  intellect  and  character.  From  the  combination  of  all 
the  accuracies  of  discrimination  with  this  and  that  length,  color, 
weight  and  the  like,  may  be  got  the  one  trait,  accuracy  in  sensory 
discrimination.  From  the  quickness  of  formation  of  each  of  a 
thousand  habits,  is  derived  the  single  trait,  rate  of  learning.  Ac- 
curacy, quickness,  efficiency,  permanence,  amount  of  improve- 
ment, rate  of  improvement,  and  acceleration  or  retardation  in  the 
rate  of  improvement,  are  important  cases  of  the  measurement  on 
one  scale  of  some  feature  of  an  individual's  condition  in  a  group 
of  traits.  Originality,  courage,  timidity,  suggestibility,  scholar- 
ship, judgment,  interest  and  curiosity  are  samples  from  a  long 
list  that  could  be  made  of  terms,  each  used  with  comparatives  to 


2o6  Educational  Psychology 

denote,  though  very  crudely,  a  man's  position  on  a  single  scale. 
This  position  or  amount  would,  however,  be  the  resultant  of  many 
manifestations  of  what  would  have  to  be  scored  as  a  combination 
of  many  traits,  if  represented  in  full,  concrete  detail. 

For  all  such  one-scale-representations  of  combinations  of  traits, 
the  entire  theory  of  single  traits  given  in  Chapter  VIII  holds  good. 
In  particular,  the  single  type  theory  holds  of  them  with  fewer 
exceptions.  For  some  one  large  cause  will  much  less  often  act 
upon  a  man  with  the  same  effect  in  all  the  traits  of  a  combination 
than  in  some  one  of  them.  So,  whereas,  in  discrimination  of  the 
tastes  of  wines  or  teas  or  the  like,  men  may  be  divided  into  an 
ordinary  and  an  expert  class,  they  will  not  be,  in  respect  to  ac- 
curacy of  sensory  discrimination  in  general.  Similarly,  though, 
in  knowledge  of  the  Latin  language,  men  may  fall  into  two  groups, 
— an  ignorant  group  and  a  group  varying  around  some  knowl- 
edge,— in  knowledge  of  languages  in  general,  they  do  not. 


CHAPTER  XI 

Extreme  Individual  Differences  :  Exceptional  Children 

From  the  discussion  of  the  distribution  of  mental  traits  in 
Chapter  VIII  it  is  evident  that,  unless  peculiar  causative  or  select- 
ive agencies  are  at  work,  there  will  be  a  few  individuals  who  will 
possess  so  little  of  any  given  capacity  or  quality  as  to  be  obviously 
'  defectives  '  in  it,  as  well  as  a  few  who  will  possess  so  much 
as  to  be  obviously  '  prodigies.'  There  will  be  a  larger  number 
who  will  possess  so  little  as  to  merit  the  popular  term  '  weak ' 
in  color  vision,  memory,  self-control,  moral  sense,  general  intelli- 
gence or  whatever  the  trait  may  be.  These,  again,  will  be  balanced 
by  an  approximately  equal  number  of  '  remarkable '  or  '  excep- 
tionally gifted.' 

If  the  mental  trait  in  question  is  the  compound  of  many  traits 
which  we  call  intelligence,  we  shall  find  at  the  lower  end  of  the 
distribution  curve  children  whom  medical  diagnosis  would  name 
idiots,  and  next  them  a  number  who  would  be  termed  imbeciles, 
and  nearer  still  to  the  average  the  group  to  whom  the  name  weak- 
or  feeble-minded  would  be  applied.  If  the  mental  trait  is  the 
compound  called  '  morality ',  the  individuals  at  the  low  extreme 
will  perhaps  be  diagnosed  as  cases  of  '  moral  insanity '  or  as 
'  moral  degenerates.'  If  the  trait  be  more  specific,  for  instance 
if  it  be  ability  to  learn  to  spell,  ability  to  learn  to  read,  cruelty, 
musical  ability,  memory,  visualizing  power  or  what  not,  we  shall 
find  few,  if  any,  special  names  for  different  degrees  of  its  posses- 
sion, though  there  will  as  truly  be  defectives  in  respect  to  any 
such  specific  mental  trait  as  in  respect  to  general  intelligence. 

The  means  which  educational  endeavor  will  use  and  the  re- 
sults which  may  be  expected  therefrom  will,  in  the  case  of  any  in- 
dividual, depend  upon  his  amount  of  the  trait  in  question.  No 
one,  unless  he  were  himself  an  '  idiot '  in  the  trait  of  common 
sense,  would  train  a  genius  and  an  idiot  alike  or  expect  them  to 
develop  alike.     At  present    there    is    a    widespread    practice    of 

(207) 


2o8  Educational  Psychology 

providing  separate  treatment  at  home  or  in  institutions  for  idiots 
and  imbeciles,  though  some  are  to  be  found  in  the  common 
schools.  And  there  is  a  growing  demand  for  institutions  and 
separate  classes  for  the  feeble-minded.  Notable  moral  defectives 
are  being  cared  for  in  separate  classes  in  some  cities.  They  also, 
when  the  parents  are  wealthy,  find  refuge  in  private  schools  of  a 
certain  type  and  in  the  somewhat  mercenary  ministrations  of 
private  tutors.  The  children  exceptional  in  their  great  superiority 
to  the  average  are  not  systematically  given  any  special  attention 
except  here  and  there  by  systems  of  rapid  promotion. 

For  the  proper  treatment  of  exceptional  children  we  need 
knowledge  of  the  exact  distribution  of  all  the  mental  traits  which 
we  desire  to  develop  or  abolish,  of  the  causes  which  determine 
an  individual's  station  in  each,  of  the  symptoms  by  which  we  may 
conveniently  find  out  any  one's  station  in  each,  and  of  the  agencies, 
educational,  hygienic  and  medicinal,  which  alleviate  or  in- 
tensify the  different  conditions.  The  last  involves  the  study  of 
the  diflferential  action  of  stimuli  upon  individuals  of  different 
stations.    For  instance,  the  training  of  idiots  should  rest  upon : — 

1.  A  consideration  of  the  distribution  of  intelligence  which 
will  tell  us  what  the  frequencies  of  different  degrees  of  low  mental 
capacity  are. 

2.  A  study  of  the  extent  to  which  original  nature  decides  an 
individual's  station  in  intelligence,  and  of  the  displacements  of 
individuals  from  their  original  station  to  a  lower  station  by  acci- 
dent, disease,  unwise  training,  and  the  like. 

3.  A  study  of  the  physical  and  mental  symptoms  which  enable 
us  to  measure  a  person  as  very,  very  low  in  intelligence. 

4.  A  study  of  the  influences  of  climate,  food,  operative  sur- 
gery, medicines,  manual  work,  school  work,  good  and  bad  ex- 
ample, etc.,  which  make  the  mental  condition  better  or  worse. 

In  the  case  of  idiocy,  imbecility  and  pronounced  feebleness 
of  mind,  psychology,  mental  pathology  and  medicine  could  show 
a  respectable  array  of  facts  for  the  student,  though  precise  quan- 
titative studies  fit  to  serve  as  models  for  study  are  very  rare.  We 
know,  at  least  roughly,  the  frequency  of  intellects  so  defective  as 
to  disturb  the  home,  resist  school  influence  and  excite  popular 
pity  or  derision  (about  i  in  500).  We  know  that,  in  all  prob- 
ability, by  original  nature  human  beings  are  distributed  approxi- 
mately  according   to   the   '  probability '   distribution,   with   some 


Extreme  Individual  Differences  209 

elimination  at  the  low  end,  and  that  selection  from  the  germs 
produced  by  one's  ancestry  decides  one's  position ;  that  the  ordi- 
nary circumstances  of  life  in  which  people  differ  do  not  much 
alter  one's  position  compared  with  his  fellows,  but  that  many 
special  influences,  e.g.,  brain  injuries,  hydrocephalus,  cretinism, 
scarlet  fever,  and  the  like,  may  displace  a  person  to  a  lower  sta- 
tion. Some  of  these  influences  probably  act  indifferently  upon 
individuals  of  all  original  stations,  so  that,  so  far  as  concerns 
them,  idiocy  may  be  caused  in  one  of  the  most  intelligent  ancestry. 
On  the  other  hand,  many  of  them  produce  idiocy  only  upon  the 
fertile  soil  of  originally  weak  mental  structure.  As  regards 
symptoms,  we  are  not  so  well  off  as  we  may  hope  to  be  in  the 
future.  Idiocy  can  not  be  recognized  as  early  in  life  as  it  should 
be.  Nor  can  it  always  be  distinguished  from  mere  backward- 
ness ;  nor  can  its  different  degrees  be  measured  with  convenience 
or  with  precision.  As  regards  treatment  for  amelioration,  we 
have  a  great  amount  of  information,  though  not  all  of  the  best 
quality. 

But  if  we  look  for  similar  information  concerning  other  men- 
tal defects  we  are  doomed  to  disappointment.  And  exceptional 
children  at  the  high  end  of  the  distribution  curve  have  been  so 
little  studied  that  the  very  words,  exceptional  and  abnormal,  are 
commonly  used  to  refer  only  to  those  exceptionally  defective.  A 
systematic  treatment  of  the  whole  subject  is  thus  out  of  the  ques- 
tion and  we  must  be  content  with  (i)  a  series  of  rather  discon- 
nected and  ill-proportioned  comments  representing  the  present 
state  of  knowledge  and  opinion  on  matters  which  concern  edu- 
cational theory  and  practice  and  (2)  an  outline  which  will  sug- 
gest what  we  ought  to  know  but  do  not. 

Exceptional  Superiority 

It  is  a  corollary  from  the  facts  of  the  last  three  chapters  that 
exceptional  superiority  exists  in  the  case  of  any  mental  trait  or 
combination  of  traits,  and  that  the  greater  the  degree  of  superior- 
ity, the  more  exceptional  it  is.  Some  of  the  obvious  and  practi- 
cally important  cases  are: — total  intelligence,  mental  balance, 
efficiency  or  capability,  energy,  quickness  of  mental  processes, 
breadth  of  mental  processes,  strength  or  intensity  of  mental  pro- 
cesses,  abstract  power,  permanence   of  memories,  mathematical 

14 


2IO  Educational  Psychology 

ability,  musical  ability,  ability  in  drawing  or  painting,  mechanical 
insight,  steadiness,  courage,  sociability,  affection  and  enthusiasm. 
The  list  might  of  course  be  indefinitely  prolonged. 

The  cause  of  exceptional  superiority  is  original  nature  plus 
or  minus  a  displacement,  commonly  slight,  due  to  environmental 
influence.  The  environment  may  displace  a  person  downward  to 
a  great  extent,  but  upward  much  less  easily.  The  forceps  of 
the  physician,  the  strain  of  disease,  the  shock  of  brain  concussion, 
may  reduce  original  superiority  to  pronounced  defect ;  but  medi- 
cine, favorable  training  and  the  impetus  of  zeal  seldom  elevate 
a  mediocre  person  to  top  rank.  In  the  case  of  the  combination  of 
gifts  which  we  call  intelligence  they  never  do ;  for  it  is  only  by 
the  concentration  of  much  energy  in  a  narrow  line  that  an  orig- 
inally inferior  person  becomes  superior.  For  him  to  do  so  in 
all  lines  is  impossible. 

The  symptoms  of  superiority  in  any  trait  are  clear  when  the 
trait  itself  can  be  directly  measured.  It  is  easy  to  tell  an  excep- 
tionally good  speller  in  school,  or  scientist  in  adult  years,  or  sol- 
dier in  war,  or  orator  in  the  pulpit.  But  when  we  have  to  infer 
the  future  from  present  and  past  symptoms  in  young  children, 
or  judge  a  general  trait  from  a  few  particular  manifestations, 
our  inferences  lack  surety  and  precision.  Superior  efhciency  in 
life's  work,  for  instance,  is  not  at  all  clearly  shown  by  superiority 
in  school  tasks ;  success  in  formal  grammar  is  not  clearly  symp- 
tomatic of  general  abstract  ability ;  the  best  boy  in  a  thousand  in 
discriminating  length  may  not  turn  out  much,  if  at  all,  above 
the  average  in  general  keenness  of  sense  discrimination.  When 
the  relationships  of  a  great  many  mental  traits  have  been  worked 
out  in  the  way  shown  in  Chapter  IX,  any  one  measurement  will 
serve  as  a  symptom  to  an  extent  now  impossible.  At  present 
a  wise  rule  is  never  to  infer  from  a  symptom  any  condition 
which  moderate  effort  will  enable  you  to  measure  directly,  and 
never  to  infer  future  conditions  from  present  symptoms  with- 
out continuing  observations  into  the  future  and  modifying  your 
inference  as  they  direct. 

The  development  in  individuals  of  a  trait  in  which  they  are 
exceptionally  superior  would  undoubtedly  be  aided  by  training 
different  from  that  of  those  who  approach  the  modal  condition, 
but  experimental  studies  must  be  made  before  any  safe  decision 
can  be  reached  as  to  what  sort  that  training  should  be. 


Extreme  Individual  Differences  211 

Exceptional  Inferiority 

The  distribution  of  mental  traits  at  the  low  end  has  not  been 
determined ;  for  the  children  accessible  to  the  scientist  in  schools 
probably  do  not  include  all  of  the  children  defective  in  any  im- 
portant particular.  Most  of  those  who  are  very  deficient  in 
general  intelligence  are  sure  to  be  secluded  at  home  or  in  institu- 
tions. Some  of  the  moral  defectives  will  be  in  reform  schools, 
or  will  be  habitual  truants  or  the  companions  of  thieves  and 
tramps,  or  will  be  in  the  care  of  private  schools  or  tutors.  To  a 
less  extent  those  very  deficient  in  memory  or  abstract  power  or 
nervous  control  will  tend  to  disappear  for  a  longer  or  shorter 
time  from  the  schools.  It  is  probable  that  the  distribution  in  many 
cases  would  deviate  somewhat  from  the  normal,  taking  a  form 
like  Fig.  30  (p.  153).  The  increase  of  defectives  over  the  prob- 
able frequency  would  be  due  to  the  action  of  environmental 
forces  which  may  lower  a  person  from  almost  any  station  but  do 
not  raise  him  far.  For  instance,  there  seem  to  be  many  more 
people  totally  blind  than  just  able  to  see,  the  passage  from  good 
eyesight  to  blindness  being  more  frequent  than  the  opposite. 

Exceptional  inferiority  characterizes  some  members  of  the 
human  species  in  almost  every  mental  trait  or  combination  of 
traits.  The  list  given  on  page  2ogi.  is  appropriate  here.  Atten- 
tion may  also  be  called  to  defects  of  the  senses ;  defects  of  atten- 
tion; defects  of  nervous  action,  e.g.,  chorea;  to  the  cases  where 
a  very  great  amount  of  a  trait  is  a  defect,  e.g.,  cruelty  or  the 
instinct  to  possess  oneself  of  what  one  desires ;  the  minor  automa- 
tisms, such  as  biting  the  nails  or  counting  groups  of  objects ; 
morbid  or  useless  impulses,  such  as  touching  every  tree  one 
passes ;  and  fetichisms,  e.g.,  great  aflfection  for  a  red  rag. 

The  causes  of  exceptional  defects  are  the  same  as  of  excep- 
tional superiority,  but,  as  has  just  been  said,  environmental  causes 
play  here  a  more  important  role.  Their  action  has  been  carefully 
studied  only  in  the  case  of  defects  of  sight,  hearing  and  general  in- 
telligence, nervousness,  choreic  disturbance,  and  the  psychological 
defects  with  which  medical  practice  deals.  To  the  medical  liter- 
ature on  these  topics  the  reader  is  referred  with  the  warning  that 
precise  quantitative  statements  will,  unfortunately,  rarely  be  given. 

What  was  said  about  symptoms  in  the  case  of  exceptional  su- 
periorities may  be  applied  equally  here.     In  the  case  of  general 


212  Educational  Psychology 

lack  of  intelligence  there  will  be  some  special  facts  to  be  noted. 
Such  additional  information  is  also  at  hand  in  the  case  of  those 
other  defects  which  have  received  the  attention  of  medical  science. 
The  reader  is  referred  to  text-books  on  sense  defects,  on  children's 
diseases  and  on  idiocy  and  imbecility. 

We  know  almost  nothing  about  the  remedial  action  of  special 
forms  of  training  upon  those  mental  defects  which  medical  prac- 
tice has  disregarded.  Leaving  to  one  side  such  means  as  should 
be  prescribed  and  administered  by  a  physician,  we  may  make 
the  following  recommendations  : — 

For  nervousness :  outdoor  life,  much  absolute  rest,  free- 
dom from  competitive  work  and  the  exciting  features  of  school 
and  social  life,  but  not  from  participation  in  both  physical  and 
mental  work. 

For  hysteria :  outdoor  life,  removal  from  the  home  environ- 
ment, calm  but  insistent  training  in  good  habits,  the  example  of  a 
well-balanced,  unemotional  teacher,  objective  interests  in  nature, 
industry  and  human  affairs,  freedom  from  the  exciting  features  of 
school  and  social  life. 

For  general  intellectual  weakness :  removal  to  a  special  insti- 
tution, a  stimulating  physical  and  mental  environment  (though 
not  for  the  few  cases  complicated  with  great  nervous  irritability),, 
stirring  physical  play,  outdoor  life,  systematic  stimulation  of 
the  senses  and  of  curiosity,  the  arousal  and  direction  of  bodily 
movements,  systematic  physical  training. 

The  teacher  or  the  consulting  psychologist  needs  the  cooperation 
of  the  physician  in  almost  all  cases  of  mental  defect.  Their  causes, 
symptoms  and  relief  are  all  connected  with  physical  changes. 
These  are  sometimes  apparent  to  the  ordinary  practitioner,  as  in 
defective  school  work  due  to  indigestion  or  nasal  or  throat  obstruc- 
tions ;  sometimes  apparent  to  the  specialist,  as  in  defective  ability  to 
read  and  spell  due  to  retinal  defects ;  sometimes  unrecognizable, 
but  yet  doubtless  existing,  as  in  defective  ability  to  form  general 
and  abstract  notions. 

General  Intellectual  Defect 

The  psychology  of  those  deficient  in  general  intellect  (idiots, 
imbeciles  and  the  feeble-minded)  has  been  discussed  at  some 
length  by  many  students.  The  chief  questions  concern  classification, 
causation,  symptoms  and  treatment.    The  aim  of  this  section  will 


Extreme  Individual  Diifcrences  213 

not  be  to  review  the  facts  and  opinions  that  have  been  stated,  but 
simply  to  help  the  reader  to  study  the  literature  of  the  subject 
intellig-ently. 

English  writers  agree  in  using  the  terms  idiots,  imbeciles  and 
feeble-minded  to  refer  in  order  to  the  three  lowest  conditions  of 
intellect.  This  common  use  makes  the  terms  very  convenient, 
but  it  is  certain  from  our  knowledge  of  the  distribution  of  mental 
traits  that  any  effort  to  separate  sharply  idiocy  from  imbecility, 
and  the  latter  from  feebleness  of  mind,  must  fail.  The  words  are 
but  names  used  roughly  for  sections  of  a  continuous  surface  of 
frequency.  The  obvious  thing  to  do  is  to  arrange  a  scale  for 
intellect  and  describe  that  of  each  individual  by  his  precise  station 
on  that  scale,  not  by  a  vague  name. 

Numerous  more  detailed  classifications  have  been  proposed,  some 
on  the  basis  of  mental  traits,  e.g.,  the  degree  of  capability  in 
attention,  the  capacity  for  feeling  relationships,  the  efficiency  of 
the  senses  and  motor  apparatus  ;  some  on  the  basis  of  the  conditions 
accompanying  them,  e.g.,  a  classification  into  paralytic  idiocy, 
epileptic  idiocy,  syphilitic  idiocy,  etc. ;  some  on  the  basis  of  causa- 
tion, e.g.,  a  classification  into  congenital  and  acquired. 

The  fact  is  that  the  varieties  of  human  nature  referred  to  by 
the  words  idiot,  imbecile  and  feeble-minded,  are  numerous,  that  all 
sorts  of  combinations  of  mental  qualities,  accompanying  diseases, 
causes  and  physical  stigmata  occur,  and  that  no  simple  classifica- 
tion can  be  adequate  for  all  purposes.  To  grade  idiots  before 
courts  of  law  or  for  treatment  in  an  asylum,  a  classification  by 
mental  ability  as  measured  by  attentiveness  or  some  other  mental 
traits  may  be  best ;  to  provide  for  medical  treatment  their  separa- 
tion into  groups  according  to  concomitant  diseased  conditions  may 
be  wise ;  for  medical  science  the  pathological  changes  in  the  brain 
correlated  with  the  mental  conditions  may  be  the  key  to  the  useful 
classification;  and  so  on  through  possible  classifications  for 
prophecy  of  amelioration,  for  educational  treatment,  and  for 
psychological  analysis. 

I  suggest  as  one  of  the  most  fundamental  and  useful  classifica- 
tions a  division  into : — ( i )  Those  whose  condition  is  due  to  original 
nature,  who  hold  the  position  in  the  scale  of  intelligence  which 
the  make-up  of  their  germs  decreed,  and  (2)  those  who  by  accident 
or  disease  have  been  displaced  downward  from  their  original 
positions  in  the  distribution  scheme.     The  condition  of  members 


214  Educational  Psychology 

of  the  first  class  should,  as  knowledge  advances,  be  capable  of 
early  diagnosis ;  they  should  possess  many  characteristics  in  com- 
mon and  allow  of  further  subclassification ;  medical  treatment 
would  be  relatively  inefficient,  but  from  wise  educational  and 
hygienic  control  we  should  expect  much.  The  second  class  would 
present  fewer  characteristics  in  common ;  strictly  medical  or 
surgical  treatment  would  be  of  more  importance  than  educational 
training ;  they  should  be  studied  in  connection  with  mental  diseases 
in  general.  Roughly  it  would  be  fair  to  say  that  for  the  first  class 
we  need  psychologists  and  special  schools,  while  for  the  second 
we  need  physicians  and  hospitals. 

It  seems  desirable  further  to  separate  children  who  are  feeble- 
minded, and  are  destined  to  remain  so,  from  those  who  are  simply 
backward  in  mental  growth  and  may  eventually  reach  a  fair 
station.  We  know  that  in  physical  growth  some  children  who 
from  six  to  twelve  or  thereabouts  are  far  below  average  stature 
for  their  age,  in  later  years  make  up  part  or  all  of  the  deficiency, 
and  there  are  many  reasons  for  believing  the  same  to  be  the  case 
with  mental  growth.  The  essentially  dull  should  never  be  con- 
fused in  theory  or  in  actual  treatment  with  those  temporarily 
deficient. 

To  the  discussions  of  the  causation  of  idiocy,  imbecility  and 
feebleness  of  mind  in  the  standard  texts  I  have  nothing  to  add 
save  that  where  so  complex  and  so  interrelated  causes  are  studied, 
great  help  will  come  from  more  precise  measurements  of  amount 
and  from  estimating  the  efficiency  of  partial  causes  by  the  coeffi- 
cients of  correlation  between  them  and  their  supposed  effects. 

In  the  case  of  the  symptoms  of  these  conditions  also,  precise 
measurements  with  objective  tests  would  permit  an  advance  in 
knowledge  which  is  impossible  so  long  as  cases  are  studied  by  an 
undefined  general  examination  and  described  by  the  loosest  of 
adjectives. 

Amongst  the  recommendations  for  educational  treatment  those 
which  are  in  accord  with  the  following  facts  should  be  given 
especial  weight :  ( i )  Learning  by  the  unconscious  selection  of 
reactions  which  produce  pleasure  and  the  elimination  of  reactions 
which  produce  pain,  is  widespread  throughout  the  animal 
kingdom  and  may  be  depended  upon  when  learning  from  explana- 
tion, insight  and  general  principles  is  impossible.  (2)  The  lower 
the  mental  capacity  of  an  individual,  the  closer  in  time  must  the 


Extreme  Individual  Differences  215 

pain  or  pleasure  follow  the  reaction.  (3)  The  connections  between 
impressions  and  obvious  movements  of  the  body  are  more  easily 
formed  than  between  impressions  and  ideas  or  the  more  subtle 
movements  of  the  muscles  of  the  face,  throat  and  trunk  which 
perhaps  always  parallel  ideas.  The  first  type  of  connections  may 
be  formed  in  individuals  incapable  of  the  second.  The  so-called 
kindergarten  and  manual-training  methods  are  therefore  particu- 
larly suited  to  defectives.  (4)  Mental  defect  often  involves  a 
sluggishness  of  action  on  the  part  of  the  nervous  system  which 
makes  a  rapid  succession  of  stimuli  interfere  with  each  other  and 
result  in  mental  confusion,  and  necessitates  the  continuation  of  the 
same  stimulus  over  a  long  interval  or  its  repetition.  (5)  The 
extreme  narrowness  of  the  field  of  attention  and  the  inability  to 
control  sudden  alternations  of  attention  from  one  topic  to  another 
and  back  make  it  necessary  for  the  teacher  to  take  up  but  one  small 
issue  at  a  time,  to  progress  along  one  single  line.  (6)  Knowledge 
of  relations,  including  appreciation  of  general  and  abstract 
notions  and  the  symbols  for  them,  is  practically  beyond  the 
capacity  of  these  inferior  minds.  It  is  therefore  wisdom  not  to 
pretend  to  give  it  and  economy  not  to  try.  They  need  sense 
training,  object-lessons  and  concrete  work  throughout.  (7)  Sug- 
gestion is  potent  here  as  elsewhere.  By  treating  the  feeble-minded 
like  normal  children  as  far  as  is  possible  we  help  to  make  them 
more  normal.  They  should  have  their  school,  church,  entertain- 
ments, trades,  excursions  and  the  like.  They  should  not  be  made 
to  appear  peculiar  in  dress  or  encouraged  in  eccentric  habits. 

Exact  Measurements  of  General  Intellectual  Defect 

Measurements  of  various  mental  traits  in  intellectually  deficient 
children  and  adults  have  been  made  by  Galton  and  Jacobs  ['87], 
Johnson  ['95],  WyHe  ['00],  Kelly  ['03],  Lobsien  [03],  Kuhl- 
mann  ['04],  Norsworthy  ['06],  Binet  and  Simon  ['09],  and 
others.  The  main  purpose  of  these  measurements  has  been  to 
describe  the  defect  more  exactly  and  to  analyze  it  into  its  factors. 
Norsworthy  attempted  also  to  measure  the  effect  of  a  year's 
growth  and  institutional  training. 

Whatever  intellectual  function  is  tested,  its  efficiency  is  found 
less  than  in  the  average  man.  The  idiots,  imbeciles  and  feeble- 
minded are  inferior  in  sense-discrimination,  memory,  the  rapidity 
and  accuracy  of  sensori-motor  habits,  quickness  of  association. 


2i6  Educational  Psychology 

span  of  attention  and  other  traits.  This  was  to  be  expected.  But 
they  are  not  equally  inferior  in  all  functions.  And  it  is  the  main 
service  of  psychological  tests  to  measure  their  relative  inferiority 
in  different  traits  and  so  verify,  refute  or  modify  existing  notions 
as  to  the  factors  involved  in  idiocy,  imbecility  and  feebleness  of 
mind. 

The  question  of  whether  a  child  is  more  inferior  in  one  trait, 
say,  memory  of  a  list  of  simple  words,  than  in  another,  say,  ability 
to  select  from  ten  dominoes  the  one  like  a  sample  shown,  is  some- 
what subtle  and  cannot  be  answered  by  simply  measuring  his 
abilities  in  the  two  cases.  Suppose  that,  of  ten  words  spoken  once, 
he  remembers  5,  and  that  in  selecting  a  domino  (the  ten  with  the 
fewest  spots  being  used)  he  takes  nine  seconds,  making  no  errors. 
From  these  records  alone  we  do  not  know  whether  he  is  inferior. 
But  even  if  it  is  known  that  the  average  person  of  his  sex  and 
age  remembers  7  such  words  in  such  a  case  and  matches  the 
domino  in  5  seconds,  the  question  of  the  defective  child's  relative 
inferiority  in  the  two  traits  is  still  unanswered.  Two  words  less 
than  seven  and  four  seconds  more  than  five  are  not  commensurate. 

They  may  be  made  commensurate  by  expressing  each  as  a 
multiple  of  the  variability  of  men  in  general  for  the  trait  in  ques- 
tion. Thus  if  the  median  deviation  of  men  in  general  from  the 
average  of  7  words  remembered  is  1.2  words,  the  defective's 
inferiority  in  memory  is  i|  times  the  median  deviation  in  memory. 
If  the  median  deviation  of  men  in  general  from  the  average 
(5  seconds)  in  matching  the  domino  is  i  second,  the  defective's 
inferiority  in  matching  dominoes  is  4  times  the  median  deviation. 
In  so  far  as  the  variability  of  men  in  general  may  be  taken  as  the 
standard  by  which  inferiority  is  to  be  measured,  he  is  4/ 1.67, 
or  2.4,  times  as  inferior  in  the  matching  test  as  he  is  in  memory. 

Now  the  variability  of  men  in  general,  though  far  from  equal 
in  all  traits,  is  a  very  useful  standard  for  the  present  purpose. 
The  ratio  of  the  defective's  deviation  from  the  central  tendency  of 
his  age  and  sex  to  that  found  in  general  is  just  what  one  needs 
to  know.  '  Worse  than  all  save  10  per  cent  in  weight,'  '  worse 
than  all  save  10  per  cent  in  height,' '  worse  than  all  save  10  per  cent 
in  memory,'  '  worse  than  all  save  10  per  cent  in  attentiveness  ' — 
may  very  usefully  be  treated  as  *  equally  inferior  in  weight,  height, 
memory  and  attentiveness.'  If  a  defective  is  in  height  as  far  below 
the  central  tendency  as  the  25  percentile  (the  median  of  all  those 


Extreme  Individual  Differences  217 

men  who  are  below  the  central  tendency),  in  weight  twice  as  far 
below,  in  memory  three  times  as  far  below,  and  in  attentiveness  five 
times  as  far  below,  he  may  usefully  be  said  to  be  five  times  as 
inferior  in  attentiveness  as  in  height,  one  and  a  half  times  as 
inferior  in  memory  as  in  weight,  and  so  on. 

Thus  in  Table  21  (arranged  from  data  given  by  Norsworthy 
['06,  pp.  54-67])  the  measures  are  all  in  terms  of  the  median 
deviation  of  the  age  and  sex  in  question  for  the  trait  in  question. 
Each  row  gives  the  measures  in  the  case  of  one  individual.  Each 
column  gives  the  measures  in  one  trait.  Each  entry  reads : 
'Individual  ....  is  ....  times  as  far  below*  the  central  tendency 
of  American  children  in  general  of  his  age  and  sex  as  is  the  25th 
child  from  the  bottom  out  of  100  children.' 

TABLE  21. 

Samples  op  Measxjrements  op  the  Feeble-Minded,  Made  Commensxjratb 
One  with  Another  by  Being  Transformed  Each  into  Multiples 
OP  THE  Median  Deviation  of  the  Trait  in  Question 
FOR  THE  Age  and  Sex  in  Question. 

Marking 
A's  and 

Discrim-    words  Mem-  Mem-  Controlled  association, 

ination  contain-  ory  of  ory  of 

of         ing  a  lists  of  sen-         Part       Genus         Opposites. 

weight,     and  t.  words,  tences.     whole,     species.         I.  II. 

A.  —  .11   —1.94  —6.73  —3-42       t  t  i         t 

B.  — 2.51     — 2.93     — 4.17     — 3.50 — 11.00    — 6.60    — 5.00    — 8.40 

C.  t  t  t        — 5.00  I  t  t        —3-82 

D.  —3-54  —1-33  —2-49  — 5-4i            t       —1300  —4.80  —6.00 

E —4.01  —2.73  —8.57—13.00  -5.65  —8.75 

F t               t  t               t  t  t 

G.        — 1. 71  —3-69  —4"  —3-33  — 10.00—16.60  — 5.65  — 8.15 

H.        -f-iii  —409  —5-36  —3-39           t         X  —4-87 

I.         —6.54  —4-42  —5-98  —3-75           t               t         t 

J —2.23    —5-30         X  X  X  X 

A  group  of  defectives  thus  rated  in  commensurate  units  may 
then  be  easily  compared,  with  respect  to  their  inferiority  in  differ- 
ent traits,  by  a  modification  of  the  method  used  for  comparing  the 
sexes  and  races.  The  modification  necessary  is  to  use  in  place  of 
'  per  cent  of  defectives  equalling  or  exceeding  the  median  ability 

*Except  for  individual  H  in  discrimination  of  weight. 

J  Signifies  that  the  individual  failed  entirely  in  the  test  in  question. 


2i8  Educational  Psychology 

of  people  in  general  of  that  age  and  sex  '  the  '  per  cent  equalling  or 
exceeding  some  lower  degree  of  ability  '  of  people  in  general,  such 
as  the  25  percentile  (or  median  of  the  half  below  the  central 
tendency)  or  the  12^^  percentile  (median  of  the  lowest  quarter  of 
people  in  general  of  the  given  age  and  sex.  For  instance,  if: — 
In  height  61  per  cent  of  defectives  are  above  the  25  percentile, 
In  discrimination  of  weight  28  per  cent  of  defectives  are  above  the 

25  percentile, 
In  memory  of  sentences  10  per  cent  of  defectives  are  above  the 

25  percentile, 
In  giving  opposites  of  words  i  per  cent  of  defectives  are  above  the 

25  percentile, 
it  is  clear  that  the  inferiority  is  greater  in  giving  opposites  than 
in  memory  of  sentences,  and  so  on. 

Of  the  investigators  of  the  psychology  of  the  intellectually 
deficient  Norsworthy  is  the  only  one  who  has  put  the  results  in 
such  a  form  as  to  measure  relative  inferiority.  Of  the  others  some 
have  not  even  measured  the  variability  of  the  defectives  or  of 
people  in  general  in  the  trait  in  question,  so  that  only  a  very  rough 
estimate  of  relative  inferiority  can  be  got  from  their  figures. 

From  the  best  estimates  that  I  am  able  to  make,  the  order  of 
inferiority  of  intellectual  traits*  in  defectives  confined  in  institu- 
tions seems  to  be : — Sensitivity,  in  which,  on  the  whole,  25  per  cent 
are  above  -i  P.  E.  Speed  and  precision  of  sensori-motor  connec- 
tions, in  which  on  the  whole  20  per  cent  are  above  -i  P.  E.  Speed 
and  precision  of  connections  between  idea  and  idea  or  between  idea 
and  act,  in  which,  on  the  whole,  i  to  10  per  cent  are  above  -i  P.  E. 
Speed  and  precision  of  selective  associations  or  of  responses  to 
parts  or  elements  of  situations,  in  which,  on  the  whole,  o  per  cent 
reach  -i  P.  E. 

The  experimental  data  do  not  give  a  very  clear  picture  and 
universally  true  analysis  of  the  condition  which  relegates 
individuals  to  the  class  idiots,  imbeciles  and  feeble-minded.  But 
they  do  show  that  such  a  clear  picture  and  uniformly  true 
analysis  is  not  to  be  expected,  and  that  individuals  thus  classified 
vary  greatly  among  themselves  in  the  nature  of  their  defects.  They 
also  show  negatively  that  no  single  defect  is  an  adequate  explana- 
tion of  their  condition.  Seguin's  notion  that  weakness  in  sensitiv- 
ity and  responsiveness  is  the  cause  of  idiocy  was  certainly  far  from 

*In  height  and  weight  about  60  per  cent  are  above  -i  P.  E. 


Extreme  Individual  Differences  219 

true.  On  the  contrary,  power  of  connection  is  relatively  much 
weaker  than  power  of  reception  or  of  action.  Sollier's  notion  that 
instability  of  thought, — lack  of  power  to  control  attention, — is  the 
cause  is  also  certainly  wrong ;  for  it  leaves  unexplained  the 
enormous  slowness  in  their  mental  operations,  including  responses 
to  situations  like  the  sight  of  food  or  the  thought  of  candy,  to 
which  attention  is  easily  given.  It  also  leaves  unexplained  their 
relatively  greater  inferiority  in  all  connections  involving  ideas  than 
in  mere  sensori-motor  connections,  like  sorting  colored  beads  or 
marking  a  familiar  letter. 

If  one  is  to  hazard  a  description  of  a  group  which  varies 
enormously  within  itself,  he  may  say  of  these  exceptionally  unin- 
tellectual  children :  They  are  weak  in  the  number,  delicacy, 
complexity,  speed  of  formation,  and  permanence  of  associations  of 
whatever  sort ;  especially  so  when  one  or  both  of  the  members  to 
be  connected  is  an  idea.  They  are  weaker  in  the  analysis  or 
abstraction  of  elements  out  of  gross  total  situations,  and  the  deter- 
mination of  thought  by  the  action  of  a  part  or  element  or  aspect 
of  a  situation.  They  are  as  a  result  weakest  in  those  functions 
which  require  the  cooperation  of  many  selected  associations  and 
the  partial  activity  of  many  relics  of  past  experiences  in  the  service 
of  some  complex  and  ideal  situation  or  problem.  They  are  also 
usually  very  weak  in  the  instinct  of  mental  activity,  in  the 
satisfaction  with  mental  life  for  its  own  sake.  They  represent  the 
extremes  of  the  condition  found  in  stupid  people  generally,  the 
opposite  of  the  gifted  person  who  connects  rapidly,  precisely  and 
permanently,  analyzes  facts  into  their  elements  easily  and  often, 
thinks  facts  together,  is  guided  by  remote  and  ideal  ends,  and 
enjoys  thinking  for  its  own  sake. 

They  are  inferior  in  sensitivity,  but  their  appearance  of  being 
very  much  so  is  due  in  part  to  their  willingness  to  live  in  mental 
torpor,  their  failure  to  connect  the  sense  impressions  with  any- 
thing further,  and  their  more  frequent  failure  to  analyze  out  color, 
size,  shape,  and  the  like  from  the  gross  total  situations  whose 
partial  aspects  they  are.  They  are  inferior  in  movement,  but 
their  appearance  of  very  great  inferiority  in  it  is  due  in  part  to 
their  failure  to  connect  movements  with  percepts  and  ideas  or  to 
analyze  out  and  get  control  over  portions  of  movement-series  and 
recombine  them  anew.  They  are  very  inferior  in  attentiveness 
from  the  point  of  view  of  one  to  whom  attentiveness  means  power 


220  Educational  Psychology 

of  attention  to  elements  rather  than  to  gross  totals,  intellectually 
fruitful  things  rather  than  the  natural  objects  of  the  instincts 
connected  with  food,  fears,  sex,  and  the  like,  or  past  and  future 
situations  rather  than  present  situations.  But  the  words  '  lack  of 
power  of  attention '  do  not  properly  explain  but  only  name  this 
fact.    The  facts  given  above  are  again  the  real  explanation. 

To  this  characterization  there  are  numerous  exceptions. 
Sensory  or  motor  defects  (especially  speech),  if  not  overcome  by 
proper  education,  may  simulate  general  intellectual  defect.  In 
special  lines  a  feeble-minded  child  may  manifest  a  fair  degree  of 
power  of  connection,  analysis  and  even  of  selection.  Learning 
may  be  (though  it  usually  is  not)  very  slow  but  very  permanent. 
And  so  on  with  many  other  divergences.  The  experimental  data 
show  abundantly  that  the  idiots,  imbeciles  and  feeble-minded  are 
subject  to  all  the  complexities  of  interrelations  of  mental  traits 
described  in  Chapter  IX.  They  are  not  to  be  thought  of  apart 
from  the  human  species  as  a  whole,  but  as  certain  very  divergent 
members  of  it,  by  no  means  alike  save  in  great  inferiority  in  the 
complex  of  traits  which  we  call  intellect. 

There  is  an  ill-defined  group  of  children  separated  roughly  from 
others  of  their  age  by  the  fact  that  they  do  not  get  on  in  school 
work  and  still  are  capable  enough  in  many  matters  to  make  unjusti- 
fiable the  title  idiot,  imbecile  or  feeble-minded,  as  commonly  tised. 
Theoretically  this  group  is  composed  of  a  number  of  different 
species  of  individuals.  Some  fail  in  school  work  because  of  defects 
of  vision  or  hearing  which  their  teachers  fail  to  allow  for.  Some 
are  nervous,  fretful  and  easily  distracted.  Some  are  extremely 
unimpressionable  and  slow.  Some  lack  only  the  capacity  to  deal 
with  abstract  ideas  and  symbols  and  succeed  well  enough  in  con- 
crete acquisition.  Some  may  possibly  possess  full  capacity  and 
lack  only  interest.  Some  are  weak  in  intellect  throughout,  belonging 
on  the  border  line  between  the  brighter  of  the  feeble-minded  and 
the  duller  of  the  so-called  normal  children.  Some  are  simply  too 
immature  for  the  work.  Practically  the  group  possesses  the  unity 
of  a  negative  characteristic,  inability  to  profit  by  the  usual  methods 
of  teaching  the  usual  subjects.  In  any  school  of  a  thousand  pupils 
the  principal  can  pick  out  from  twenty  to  forty  such  children,  who 
are  the  despair  of  their  teachers,  a  hindrance  to  their  classmates, 
and  a  source  of  worry  to  their  parents.  Even  after  sense  defects 
are  corrected  or  allowed  for,  after  adenoids  have  been  removed, 


Extreme  Individual  Differences  221 

even  when  wise  teaching  prevents  excitement  and  nervous  worry 
and  arouses  interest,  a  majority  of  these  will  be  just  as  they  were 
before.  The  group  thus  left  has  not,  until  recently,  attracted  the 
attention  of  medical  science  or  of  educational  psychology  to  the 
extent  that  its  practical  importance  deserves. 

Nors worthy  ['06]  gives  data  for  the  comparison  of  such  a  group 
of  30  girls,  8-13  years  old,  picked  out  from  about  a  thousand  in  a 
city  school  on  the  ground  of  inability  to  profit  by  the  regular 
school  work,  with  ordinary  children  of  the  same  age  who  lived  in 
the  same  environment,  attended  the  same  school  and  were 
measured  by  identical  tests  given  by  the  same  individual.  In 
giving  instructions  explanations  were  made  very  clearly  and  the 
process  required  was  also  shown  by  samples  put  upon  the  board. 
The  measurements  taken  were  as  follows: 

1.  Height. 

2.  Weight. 

3.  Body  temperature  (taken  at  the  mouth). 

4.  Pulse. 

5.  Rate  of  movement;  tested,  {a)  by  the  number  of  crosses  made  in  ten 
seconds  (two  trials) ;  (6)  by  the  number  of  up-and-down  movements  made 
in  ten  seconds  (two  trials). 

6.  Accuracy  of  movement;  tested,  (o)  by  the  number  of  touches  made 
in  drawing  a  line  between  the  lines  of  a  maze;  (b)  by  the  regularity  and 
evenness  of  the  figures  made  in  the  tests  for  the  rate  of  movement. 

7.  Efficiency  of  perception  (rate  and  accuracy  combined)  ;  tested  by 
the  A  test. 

8.  Efficiency  of  perception  (rate  and  accuracy  combined) ;  tested  by  the 
a-t  test. 

9.  Delicacy  of  discrimination  of  length;  tested  by  the  variable  error  in 
drawing  a  line  equal  to  a  lo-cm.  line  (ten  trials). 

10.  Efficiency  in  a  test  of  perception  and  movement  combined,  viz.,  the 
time  taken  to  insert  variously  shaped  blocks  into  a  board  made  with  depres- 
sions to  fit  them. 

11.  Memory  of  unrelated  words;  number  remembered  out  of  ten  after 
a  single  hearing  (two  trials) — red,  dog,  day,  tree,  buy,  never,  sick,  song, 
boy,  box,  long,  green,  arm,  inch,  true,  run,  dress,  break,  friend. 

12.  Memory  of  related  words;  number  remembered  out  of  ten  after  a 
single  hearing  (two  trials) — school,  teacher,  book,  desk,  pen,  read,  write,  add, 
spell,  word,  river,  water,  broke,  flow,  ice,  cold,  winter,  snow,  sled,  skate. 

13.  Semi-logical  memory;  memory  of  four  simple  dictations,  viz.,  (i) 
I  have  one  head,  two  eyes,  two  hands  and  ten  fingers.  (2)  I  sit  in  my  seat. 
I  read  from  a  book.  I  write  with  a  pencil.  (3)  One  and  two  are  three. 
Three  and  four  are  seven.  Five  and  six  are  more  than  ten.  (4)  In  the 
morning  I  go  to  school.     After  school  I  play.     At  night  I  go  to  bed. 

14.  Ability  in  the  formation  of  abstract  notions,   the  appreciation  of 


222 


Educational  Psychology 


relationships  and  the  control  of  associations;  measured  by  the  following 
tests:  (A)  to  write  the  opposites  of  a  given  list  of  words;  (B)  to  mark  those 
words  in  a  list  which  are  names  of  things;  (C)  to  write  a  word  representing 
some  kind  of  the  thing  named  by  a  given  word;  (D)  to  write  a  word  repre- 
senting some  thing  of  which  the  thing  named  by  the  given  word  is  a  part; 
(£■)  to  write  the  opposites  of  a  list  of  words,  the  converse  of  the  list  used  in 
A,  after  the  correct  responses  for  A  have  been  read  to  the  class. 

The  detailed  results  of  the  comparison  can  not  be  given  here. 
Their  general  outcome  is  perfectly  clear.  In  the  physical  traits 
there  is  very  little  difference  except  in  the  rise  of  temperature  at 
the  mouth  in  the  course  of  twenty  minutes  of  work  at  the  tests. 
This  invariably  occurred  with  ordinary  children,  but  in  only  60 
per  cent  of  the  special  cases.    The  pulse  rate  of  the  special  cases 


5  -4-3-2-1012346 


-8  -7  -6  -5  -4  -3  -2, 

Fig.  70.  The  relative  frequencies  of  different  degrees  of  ability  in  respect 
to  trait  14  above,  in  the  case  of  73  mediocre  nine-year-old  girls  (upper 
diagram)  and  19  girls  from  eight  and  a  half  to  thirteen  years  old,  in  a 
'special  class'  in  a  public  school  (lower  diagram).  The  units  of  the  scale 
are  multiples  of  the  median  deviation  of  nine-year-olds. 


is  a  trifle  lower.  The  difference  increases  as  we  pass  from  physical 
traits  to  tests  of  movement,  then  to  tests  of  verbal  memory  and 
then  to  tests  of  perception,  but  even  in  the  last  case  the  special 
cases  rank  about  with  the  lower  half  of  ordinary  children.  But 
with  tests  12,  13  and  14  the  difference  becomes  increasingly  greater, 
until  in  the  last  the  special  cases  come  to  rank  as  the  extreme  end 
of  the  school  population  of  their  age  (Fig.  70). 

The  one  chief  and  essential  characteristic  of  these  children  is 


Extreme  Individual  Differences  223 

thus  their  inabiHty  to  think  in  symbols,  or  with  relationships,  or  in 
such  a  way  as  to  let  a  number  of  processes  combine  to  decide  what 
a  given  thought  or  reaction  shall  be.  Concrete  facts  they  can  think 
of  and  respond  to  one  by  one,  but  they  can  not  think  in  symbols 
that  stand  for  groups  of  facts  or  elements  in  facts.  Nor  can  they 
think  facts  together  in  causal  or  other  series,  or  respond  correctly 
to  related  groups.  In  short  they  are  the  weakest  members  of  a 
school  population  in  thinking  of  the  pure  human  type.  Besides 
this  main  defect  there  is  a  diminution  of  mental  vigor,  quickness 
and  tenacity  along  all  lines.  In  no  mental  tests  do  they  do  as 
well,  and  they  give  us  some  reason  to  believe  that  as  they  grow 
older  they  will  develop  continually  less  and  less  rapidly  than 
ordinary  children  and  so  fall  farther  and  farther  behind  in  the 
mechanical  as  well  as  rational  capacities. 

Moral  Defectives 

There  are  no  general  conclusions  based  upon  exact  measurements 
of  moral  deficiency  and  its  causes  and  accompaniments.  There  is 
an  abundance  of  ineffective  detail  stored  up  in  medical  comments 
upon  so-called  moral  insanity  and  morbid  impulses,  in  prison 
reports  and  in  the  minds  of  experienced  schoolmasters.  The 
greater  complexity  of  the  phenomena  will  always  make  the 
psychology  of  moral  defectives  more  intricate  than  that  of  the 
feeble-minded. 

The  one  general  truth  which  can  be  asserted  is  that  all  sorts  of 
moral  defects  exist,  are  far  from  perfectly  correlated,  and  are  due 
to  a  multiplicity  of  causes.  There  are  extremes  of  cruelty,  deceit, 
egotism,  passion,  knavery,  destructiveness  and  of  all  immoralities 
conceivable.  There  are  boys  and  girls  notably  defective  in  only 
a  single  respect  and  others  in  whom  every  meanness  and  vice  seems 
to  thrive.  We  imagine,  however,  and  probably  with  justice,  that 
the  correlations  between  certain  defects  are  particularly  high, 
so  that  certain  combinations  of  traits  are  specially  frequent. 

Such  are  perhaps  features  of  moral  defect  characterized  by: 
(i)  Brutishness,  extreme  predominance  of  the  animal  instincts, 
shown,  for  instance,  by  brutality  and  teasing,  excessive  sexual 
appetites,  fits  of  rage  and  sulking,  unreasoning  greed  and 
malice;  (2)  extreme  egotism  and  lack  of  appreciation  of 
the  feelings  and  rights  of  others;  (3)  extreme  weakness 
of    control    and    moral    instability,    shown    by    susceptibility    to 


224  Educational  Psychology 

all  temptations  and  petty  vices,  alternations  of  affection  with 
cruelty,  anger  with  tears,  peevishness,  untrustworthiness, — an 
hysterical  and  irresponsible  mental  type,  bad  more  because 
of  the  weakness  of  good  habits  than  because  of  the 
strength  of  evil  impulses ;  (4)  the  existence  of  one  or  more 
morbid  impulses  of  an  immoral  sort.  Children  may  have  intense 
desires  to  cut  or  tear,  without  being  generally  extremely  cruel ;  to 
run  away  from  home  and  live  a  tramp  life,  without  being  generally 
extremely  disobedient ;  to  be  kleptomaniacs  but  generally  fairly 
honest ;  to  be  incendiaries  without  general  destructiveness ;  or  to 
be  sexually  disordered  without  being  of  excessive  passions. 

Of  course  there  is  no  rigid  adherence  to  these  types.  Combi- 
nations, intermediate  conditions  and  children  falling  outside  these 
groups  all  exist.  The  extent  to  which  such  a  grouping  of  cases 
is  allowable  or  useful  can  be  told  only  after  measurements  of  the 
correlations  between  special  immoral  traits  have  been  made. 

Brutishness  would  seem  likely  to  be  due  to  original  nature 
accentuated  or  relieved  by  training ;  egotism  would  seem  to  be  an 
original  defect  in  sympathy  coupled  with  lack  of  abstract  intellec- 
tual power  and  commonly  made  worse  by  the  spoiling  and  selfish- 
ness of  parents ;  moral  instability  seems  to  be  due  to  original 
nervous  instability  displayed  in  moral  more  than  intellectual 
matters  as  a  consequence  of  feeble  and  vacillating  parental  inter- 
ference. The  morbid  impulses  of  a  special  sort  are  probably  more 
ingrained  in  original  nature  and  less  influenced  by  environmental 
conditions. 

General  moral  defect  commonly  involves  intellectual  inferiority. 
Woods  ['06]  and  Pearson  ['07]  find  the  correlation  between 
intellect  and  character  to  be  about  .5.  The  brightness  and 
precocity  that  seem  to  characterize  many  cases  of  egotism  and 
moral  instability  are  really  glibness,  pertness  and  lack  of  restraint. 
It  is  therefore  likely  that  general  moral  defect  is  due  in  part  to 
generally  inferior  nervous  organization. 

Exceptional  Rates  of  Growth 
Precocity,  retarded  development*  and  arrested  development  are 
terms  loosely  used  to  refer  to  children  who  are  exceptional  in  the 

*  The  term  retarded  development  is  at  times  used  not  for  an  undefined 
slowness  of  growth,  but  for  a  slowness  in  growth  which  will  later  be  made 
up.  I  shall  therefore  replace  the  two  uses  of  the  single  term  by  the  two 
terms  slow  growth  and  delayed  growth. 


Extreme  Individual  Differences  225 

rate  of  mental  growth.  As  we  find  them  in  books  they  hardly 
mean  anything-  more  definite  than  very  rapid  growth,  very  slow 
growth,  and  absence  of  growth.  But  they  may  be  made  exact 
descriptive  terms  by  the  establishment  of  standards  of  change 
with  age  from  which  exceptional  rates  may  be  measured. 

By  far  the  best  arrangement  would  be  to  give  stations  above  or 
below  the  average  in  rate  of  growth  in  just  the  same  way  as  is 
done  in  the  case  of  static  conditions  of  a  trait,  and  to  speak  in  terms 
of  these  numerical  stations  rather  than  in  the  vague  terms  super- 
normal, normal,  subnormal,  and  the  like.  If  any  individual's  rate 
belongs  to  a  distinct  species  of  mental  growth  the  fact  can  easily 
be  made  clear  by  giving  the  total  distribution  scheme  as  well  as 
his  station  therein. 

As  a  matter  of  fact,  precocity,  retarded  development,  etc.,  are 
rarely  measured  thus  directly  from  the  rate  of  change.  Instead, 
they  are  inferred  from  the  fact  that  an  individual  is  above  or  below 
the  condition  usual  at  his  age.  The  term  retarded  development, 
for  instance,  is  thus  applied  to  a  case  which  may  be  one  of  slow 
rate  of  growth  at  the  time  of  observation,  or  of  a  slow  rate  in 
years  long  past,  or  of  low  initial  station.  This  is  unjustifiable. 
Exceptional  degrees  of  ability  should  be  dealt  with  apart  from 
exceptional  rates  of  change  in  ability. 

Precocity 

There  is  a  popular  opinion  much  encouraged  by  physicians  that 
children  who  in  early  life  grow  mentally  very  rapidly  and  so 
attain  high  stations,  are  likely  to  come  to  grief,  and  be  soon  sur- 
passed in  health  and  mental  ability  by  their  less  precocious  fellows. 
It  is  an  illustration  of  the  superficiality  of  human  thinking  that 
so  unhesitating  an  acceptance  should  be  given  to  the  paradox  that 
rapid  mental  improvement  from  birth  to  the  age  of  ten  should  be 
an  evil,  but  from  twenty  to  forty  the  greatest  of  blessings.  For, 
if  we  pass  beyond  a  few  striking  examples  which  prove  nothing, 
it  is  hard  to  see  any  evidence  for  the  first  statement  of  the  paradox. 
On  the  contrary,  bad  physique  and  nervousness  accompany  dull- 
ness oftener  than  brightness ;  and  early  mental  superiority  is 
prophetic  of  later. 

Men  and  women  of  eminent  achievements  in  life  are  far  more 
likely    to    be    precocious    in    childhood    than    ordinary,    dull    or 
inefficient  men  are.     Havelock  Ellis  ['04,  p.  136  ff.]  writes: — 
15 


226  Educational  Psychology 

"The  chief  feature  in  the  childhood  of  persons  of  eminent 
intellectual  ability  brought  out  by  the  present  data  is  their 
precocity.  This  has  indeed  been  emphasized  by  previous  inquiries 
into  the  psychology  of  genius,  but  its  prevalence  is  very  clearly 
shown  by  the  present  investigation.  It  has  certainly  to  be  said  that 
the  definition  of  '  precocity '  requires  a  little  more  careful  con- 
sideration than  it  sometimes  receives  at  the  hands  of  those  who 
have  inquired  into  it,  and  that  when  we  have  carefully  defined 
what  we  mean  by  '  precocity  '  it  is  its  absence  rather  than  its 
presence  which  ought  to  astonish  us  in  men  of  genius.  Judging 
from  the  data  before  us,  there  are  at  least  three  courses  open  to  a 
child  who  is  destined  eventually  to  display  pre-eminent  intellectual 
ability.  He  may  (i)  show  extraordinary  aptitude  for  acquiring 
the  ordinary  subjects  of  school  study;  he  may  (2),  on  the  other 
hand,  show  only  average,  and  even  much  less  than  average,  apti- 
tude for  ordinary  school  studies,  but  be  at  the  same  time  engrossed 
in  following  up  his  own  preferred  lines  of  study  or  thinking;  he 
may,  once  more,  (3)  be  marked  in  early  life  solely  by  physical 
energy,  by  his  activity  in  games  or  mischief,  or  even  by  his 
brutality,  the  physical  energy  being  sooner  or  later  transformed 
into  intellectual  energy."     ['04,  pp.  136-137.] 

"  Although  we  have  to  make  allowance  for  ignorance  in  a  large 
proportion  of  cases,  and  for  neglect  to  mention  the  fact  in  many 
more  cases,  the  national  biographers  note  that  292  of  1030  eminent 
persons  on  our  list  may  in  one  sense  or  another  be  termed  preco- 
cious, and  only  44  are  mentioned  as  not  precocious.  Many  of  the 
latter  belong  to  the  second  group,  ....  those  who  are  already 
absorbed  in  their  own  lines  of  mental  activity, — and  are  really  just 
as  '  precocious '  as  the  others ;  thus  Cardinal  Wiseman  as  a  boy 
was  '  dull  and  stupid,  always  reading  and  thinking ' ;  Byron 
showed  no  aptitude  for  school  work,  but  was  absorbed  in  romance, 
and  Landor,  though  not  regarded  as  precocious,  was  already  pre- 
paring for  his  future  literary  career.  In  a  small  but  interesting 
group  of  cases,  which  must  be  mentioned  separately,  the  mental 
development  is  first  retarded  and  then  accelerated ;  thus  Chatterton 
up  to  the  age  of  six  and  a  half  was,  said  his  mother,  '  little  better 
than  an  absolute  fool,'  then  he  fell  in  love  with  the  illuminated 
capitals  of  an  old  folio,  at  seven  was  remarkable  for  brightness, 
and  at  ten  was  writing  poems ;  Goldsmith,  again,  was  a  stupid 
child,  but  before  he  could  write  legibly  he  was  fond  of  poetry  and 


Extreme  Individual  Differences  227 

rhyming,  and  a  little  later  he  was  regarded  as  a  clever  boy ;  while 
Fanny  Burney  did  not  know  her  letters  at  eight,  but  at  ten  was 
writing  stories  and  poems."    ['04,  pp.  140- 141.] 

"  The  very  marked  prevalence  of  an  early  bent  towards  those 
lines  of  achievement  in  which  success  is  eventually  to  be  won  is 
indicated  by  the  fact  that  in  those  fields  in  which  such  bent  is 
most  easily  perceived  it  is  most  frequently  found.  It  is  marked 
among  the  musicians,  and  would  doubtless  be  still  more  evident  if 
it  were  not  that  our  knowledge  concerning  British  composers  is 
very  incomplete.  It  is  specially  notable  in  the  case  of  artists.  It 
is  reported  of  not  less  than  40  out  of  64  that  in  art  they  were  '  pre- 
cocious ' ;  only  four  are  noted  as  not  being  specially  precocious." 
['04,  p.  142.]* 

In  the  case  of  70  children  chosen  at  random,  for  each  of  whom 
I  had  records  of  ability  in  the  school  work  of  grade  4  and  of 
grade  7  or  8,  that  is  at  about  the  tenth  and  about  the  fourteenth 
and  fifteenth  years,  I  find  the  relationship  between  the  abil- 
ity shown  in  the  early  and  that  shown  in  the  later  period  to  be 
not  at  all  one  of  antagonism  but  of  resemblance.  The  Pearson 
coefficients,  uncorrected  for  attenuation,  are : 

r  for  4-7  grade   (40  cases)  r=+.i8 

r  for  4-8  grade  (30  cases)  =+.31 

If  corrected  for  attenuation  they  would  probably  be  about  ,3  and  .5. 

The  mistake  current  in  educational  literature  seems  to  have 
arisen  from  a  number  of  fallacies.  First,  physicians  meet  with 
cases  of  physical  or  mental  breakdown  in  mentally  superior  chil- 
dren. They  still  oftener  meet  similar  cases  in  mentally  inferior 
children,  but  the  former  cases  excite  more  pity  and  are  more 
interesting  and  dramatic.  They  tend,  therefore,  to  remain  in  the 
physician's  mind  while  the  others  fade.  Second,  an  interest  in 
and  acquaintance  with  topics  suitable  for  older  people,  such  as 
sex,  theology  or  adult  human  social  relations,  is  often  taken  to 
be  the  sign  of  a  precocious  mind.  Now  these  phenomena  are  often 
morbid  and  may  therefore  well  go  with  an  unstable  mental  organi- 
zation and  so  be  somewhat  prophetic  of  disaster.  But  they  are 
not  per  se  indicative  of  superior  mental  growth.  For  the  few 
supernormal  children  who  exercise  their  gifts  on  such  questions, 
there  are  many  who  are  ahead  in  school,  play,  leadership  and 
accomplishments.    One  should  not  take  the  word  precocious  in  the 

*Loewenfeld  ['03]  corroborates  the  findings  of  Ellis.  The  same  result 
has  been  obtained  by  other  writers  also. 


228  Educational  Psychology 

bad  sense  of  unbalanced  superior  gifts  and  argue  from  premises 
thus  obtained  to  conclusions  about  precocity  in  the  sense  of  gen- 
erally supernormal  mental  growth.  In  the  third  place,  physicians 
often  take  the  word  of  the  parents  for  the  children's  precocity.  It 
then  means  probably  mere  forwardness,  ready  talk,  so-called 
'  bright '  sayings  and  doings,  and  even  impertinence.  These  all 
witness  to  inferiority  disguised  by  lack  of  inhibition.  The  quiet 
child  thinks  of  many  much  brighter  things  to  say,  but  also  has  the 
strength  of  mind  not  to  say  them.  Lack  of  inhibition  and  im- 
pertinence are  prophetic  of  poor  mental  growth  in  the  future  be- 
cause they  are  indicative  of  it  in  the  past  and  present  as  well. 
Finally  it  must  be  said  that  the  average  medical  man  in  his  ignor- 
ance of  the  subtle  hereditary  and  environmental  causes  of  mental 
breakdown  grasps  at  any  cause  he  can.  If  the  child  is  dull,  mental 
weakness  is  to  blame ;  if  he  is  bright,  precocity ! 

Slow  Growth 

In  the  absence  of  any  quantitative  studies  of  slowness  of 
growth,  this  section  will  be  limited  to  brief  comments  upon  the 
question  as  to  whether  slowness  of  growth  in  one  mental  trait 
implies  equal  slowness  in  the  growth  of  others,  and  the  question 
of  the  desirability  of  a  slow  mental  growth. 

Slowness  of  mental  growth  is  undoubtedly  specialized,  though 
to  just  what  extent  is  not  known.  An  obvious  illustration  is 
given  by  the  sex  instincts,  which  may  mature  far  in  advance  of 
or  far  behind  the  intellectual  powers.  So  also  with  social  facility 
or  musical  talents.  The  resemblances  between  traits  in  an  indi- 
vidual in  their  rate  of  maturing  are,  however,  probably  much 
greater  than  in  their  final  condition. 

Slowness  of  mental  growth  is  in  general  an  unfavorable  sign. 
It  is  correlated  slightly  with  low  original  capacity  and  low  ulti- 
mate attainment.  In  some  cases,  of  course,  the  growth  is  only 
delayed  and  the  individual  who  seems  to  be  far  behind  may  come 
out  well  ahead.  Moreover,  as  in  height  the  boys  who  grow  less 
than  the  average  from  twelve  to  fourteen  grow  more  than  the 
average  from  fourteen  to  sixteen,  so  in  mental  traits  retardation 
before  puberty  may  mean  acceleration  after  it. 

The  opposite  view,  a  corollary  to  the  superstition  about  pre- 
cocity, has  gained  credence,  I  fancy,  first  because  of  the  supposed 
slowness  of  maturing  of  superior  races,  and  secondly  because  of 


Extreme  Individual  Differences  229 

the  supposed  ill  success  at  school  of  gifted  men.  But  the  ap- 
parent mental  attainments  of  children  of  inferior  races  may  be 
due  to  lack  of  inhibition  and  so  witness  precisely  to  a  deficiency 
in  mental  growth.  Moreover,  we  can  not  argue  from  inferior 
races  to  inferior  members  of  one  race.  The  failure  at  school  work 
of  children  destined  to  become  eminent  men  is  a  myth.  The  per- 
centage is  far  higher  for  thieves  and  paupers  and  lack-wits. 

Inefficiency  due  to  slow  mental  growth,  especially  in  those 
cases  where  the  future  will  prove  it  to  have  been  only  delayed 
mental  growth,  must  not,  however,  be  confused  with  inefficiency 
due  to  inevitable  incapacity.  The  correlation  would  have  to  be 
1. 00  to  permit  the  interchange  of  these  terms  as  synonyms. 

Accurate  tests  to  differentiate  inherent  incapacity  from  im- 
maturity would  seem  to  be  of  great  practical  value.  They  would 
prevent  the  injustice  and  discouragement  due  to  mistaking  the 
second  for  the  first  and  the  false  hopes  inspired  by  mistaking  the 
first  for  the  second.  An  approximation  to  such  a  differential 
diagnosis  can  be  made  by  using  the  following  tests : — 

A.  Tests  of  Maturity  Chiefly. 

Motor  control  (rate  of  tapping,  rate  of  making  crosses,  maze  tests). 
Memory  of  unrelated  words,  pictorial  forms,  etc. 
Perception  {A  test,  a-t  test,  geometrical  forms  test). 
Delicacy  of  sense  discrimination  (of  length  and  of  weight). 

B .  Tests  of  Intelligence  Chiefly. 

Logical  memory  (memory  of  passages  that  involve  connected  and  sys- 
tematic exposition  or  argument). 

Controlled  association  (alphabet  and  easy  opposite  tests  or  the  like). 

Preception  of  relations  (filling  up  the  blanks  in  passages  like  the  fol- 
lowing) : 

In  everything  that  we  do  .  .  .  need  ...  be  both  quick  .  .  .  careful  .  .  . 
we  are  .  .  .  quick  we  do  not  get  much  done we care- 
ful we  do  not  do  our  work  .  .  .  well  .  .  .  others.  It  is  better  to  be  careful 
...  .  than  to  be  quick  .  .  .  the  best  worker  .  .  .  the  one  .  .  .  can  do  .  .  . 

things  .  .  .  do  .  .  .  well we  can  not  all  be  the  best,  we  can  .  .  . 

improve. 

Let  us  suppose  a  boy  who  does  not  get  on  well  in  school  to  be 
tested  and  given  stations  in  A  and  B  with  reference  to  the  median 
for  his  age  and  sex.  The  lower  his  station  is  in  A  and  the  higher 
it  is  in  B,  the  more  chance  there  is  that  he  will  grow  out  of  his 
difficulty.  Conversely,  the  higher  his  station  is  in  A  and  the 
lower  it  is  in  B,  the  greater  is  the  probability  that  he  is  essentially 
dull. 


230  Educational  Psychology 

Arrested  Development 

The  phrase  '  arrested  development '  is  used  in  medicine  to 
mean  just  what  it  says.  Bodily  organs,  including  the  brain,  may 
remain  stationary  or  nearly  so  in  one  individual  at  a  period  when 
in  the  great  majority  they  are  growing.  In  the  case  of  the  brain 
there  may  be  no  arrest  apparent  in  gross  structure,  and  yet  the 
neurones  themselves  may  not  have  attained  their  full  develop- 
ment in  complexity  and  delicacy.  If  we  knew  fully  the  history  of 
the  growth  (normal  or  pathological)  of  the  neurones  themselves, 
we  could  probably  extend  the  conception  of  arrested  development 
to  the  entire  field  of  mental  life  and  distinguish  in  post-mortem 
examinations  between  the  clodhopper  who  stagnates  mentally  after 
a  score  of  years,  and  the  Gladstone  or  Virchow  whom  the  allotted 
span  of  life  leaves  still  progressing,  as  we  now  distinguish  be- 
tween the  brains  of  an  amaurotic  idiot  and  an  average  boy.  It 
seems,  therefore,  justifiable  to  use  the  phrase  '  arrested  develop- 
ment '  from  the  psychological  point  of  view  in  the  case  of  any 
mental  trait  in  any  individual  which  remains  stationary  or  nearly 
so  at  a  period  when  it  ordinarily  is  advancing.  Medical  men  com- 
monly apply  the  phrase  to  only  those  well-marked  cases  of  general 
mental  weakness  which  are  correlated  with  gross  developmental 
defects  of  the  body  or  brain. 

Arrest  may  be  temporary  or  permanent.  In  the  former  case 
sickness,  low  nutrition  and  disuse  are  the  probable  causes  ;  in  the 
latter,  definite  brain  lesions  or  original  lack  of  developmental 
force.  It  may  be  general  or  specialized.  In  every  trait  perma- 
nent arrest  comes  sooner  or  later  to  almost  all  of  us.  The  dif- 
ferences amongst  men  are  not  in  its  presence  or  absence,  but  in 
its  date.  There  is,  of  course,  no  absolute  date  for  any  trait 
which  is  '  normal '  for  it.  The  date  is  variable,  and  abnormality 
here  as  elsewhere  can  mean  only  some  arbitrarily  chosen  difference 
from  the  average. 


APPENDIX    I 

List  of  Authors  and  Titles  Referred  to  Specifically  in  the  Text 

Betts,  G.  H '09,    The  Distribution  and  Functions  of 

Mental  Imagery,  Columbia  Univer- 
sity Contributions  to  Education, 
Teachers  College  Series,  No.  26. 

Binet,  A '97,  Psychologic  individuelle:  La  des- 
cription d'un  objet,  L'annee  psy- 
chologique,  vol.  3,  pp.  296-332, 
and,  La  description  d'une  cigarette, 
Revue  de  Psychiatrie,  1897,  pp. 
235-243. 

Binet,  A.,  and  Simon,  Th '09,    L' intelligence  des  imbeciles,  L'annde 

psychologique,  vol.  15,  pp.  1-147. 

Brown,  W '09,    Some     Experimental     Results     in 

Correlation. 

Bruner,  F.  G '08,    The  Hearing  of  Primitive  Peoples, 

Archives  of  Psychology,  No.  11. 

Burris,  W.  P '03,  The  Correlations  of  the  Abilities  In- 
volved in  Secondary  School  Work, 
Columbia  Contributions  to  Phil., 
Psy.  and  Ed.,  vol.  11,  No.  2,  pp. 
16-28. 

Burt,  C '09,  Experimental  Tests  of  General  In- 
telligence, British  Journal  of  Psy- 
chology, vol.  3,  pp.  94-177. 

Cattell,  J.  McK '03,    A  Statistical  Study  of  Eminent  Men, 

Popular  Science  Monthly,  vol.  62, 
PP-  359-377- 
06,  A  Statistical  Study  of  American 
Men  of  Science,  III.  The  Distri- 
bution of  A  merican  Men  of  Science, 
Science,  Dec.  7,  1906. 

Cornman,  O.  P '02,    Spelling  in  tfie  Elementary  School; 

An  Experimental  and  Statistical 
Investigation. 

(231) 


232 


Educational  Psychology 


Courtis,  S.  A '09,  Measurement  of  Growth  and  Effi- 
ciency in  Arithmetic,  Elementary 
School  Teacher,  vol.  10,  pp.  58- 
74.  177-199- 

Davenport,  C.  B '10,    Eugenics. 

De  Candolle,  A '73,    (Second  edition,  '85),  Histoire  des 

sciences  et  des  savants  depuis  deux 
Steele s,  etc. 

Earle,  E.  L '03,    The  Inheritance  of  the  Ability  to 

Learn  to  Spell,  Columbia  Contri- 
butions to  Phil.,  Psy.  and  Ed., 
vol.  II,  No.  2,  pp.  41-44. 

Ellis,  H '94,  '04,    (Fourth   edition,    '04),   Man   and 

Woman. 

'04,    A  Study  of  British  Genius. 

Fay,  E.  A '98,    Marriages  of  the  Deaf  in  America. 

Galton,  F '69,  '92,    Hereditary    Genius:     An    Inquiry 

into  its  Laws  and  Consequences, 
(first  edition  '69,  second  edition 
'92).  References  are  to  second 
edition. 

'83,  Inquiries  into  Human  Faculty  and 
its  Development. 

'87,  Supplementary  Notes  on  Prehen- 
sion in  Idiots,  Mind,  vol.  12,  pp. 
79-82. 

'89,  Natural  Inheritance. 
Gilbert,*^J.  A '94,  Researches  on  the  Mental  and  Phy- 
sical Development  of  School-Child- 
ren; Studies  from  the  Yale  Psy- 
chological Laboratory,  vol.  2,  pp. 
40-100. 
Heymans,  G.,  and  Wiersma,  E.,     '06  (a),     Beitrdge  zur  speziellen  Psychologic 

auf  Grund  einer  Massenuntersuch- 
ung,  Zeitschrift  f{ir  Psychologic, 
vol.  42,  pp.  81-127,  258-301. 
'06  (b),  Beitrdge  zur  speziellen  Psychologic 
auf  Grund  einer  Massenuntersuch- 
ung,  Zeitschrift  ftir  Psychologic, 
vol.  43,  pp.  321-373- 

'07,  Beitrdge  zur  speziellen  Psychologie 
auf  Grund  einer  MassenuiUersuch- 
ung,  Zeitschrift  f{ir  Psychologie, 
vol.  45,  pp.  1-42. 

'08,  Beitrdge  zur  speziellen  Psychologie 
auf  Grund  einer  Massenuntersuch- 
ung,  Zeitschrift  fur  Psychologie, 
vol.  46,  pp.  321-333. 


Authors  and  Titles  233 

Jacobs,  J '87,    Experiments  on  Prehension,  Mind , 

vol.  12,  pp.  75-79- 

Jacoby,  P '81,    (Second  edition,  '04),  Etudes  sur 

la  selection  dans  ses  rapports  avec 
I'heredite  chez  I'homme. 

Johnson,  G.  E '95,    Contribution  to  the  Psychology  and 

Pedagogy  of  Feeble-Minded  Child- 
'95,   ren,  Pedagogical  Seminary,  vol.  3, 
pp.  246-301. 

Kelly,  R.  L '03,    Psycho-physical    Tests    of  Normal 

and  Abnormal  Children — A  Corn- 
par  ative  Study,  Psychological  Re- 
view, vol.  10,  pp.  345-372. 

Krueger,  F.,  and  Spearman,  C '06,    Die  Korrelation  zwiscken  verschie- 

denen  geistigen  Leistungsfdhig- 
keiten,  Zeitschrift  fvir  Psychologic, 
vol.  44,  pp.  50-114. 

KuUmann,  F '04,    Experimental    Studies    in    Mental 

Deficiency,  American  Journal  of 
Psychology,  vol.  15,  pp.  391-446. 

Learoyd,  M.  W '96,    The    Continued    Story,    American 

Journal  of  Psychology,  vol.  7, 
pp.  86-90. 

Lecl^re,  A '98,    Description  d'unobjet,  L'annee  psy- 

chologique,  vol.  4,  pp.  379-3B9. 

Lobsien,  M '03,    Einige    Untersuchungen   fiber    das 

Geddchtniss  bei  Schwachbefdhigten, 
Die  Kinderfehler,  vol.  8,  pp.  157- 
168  and  193-203. 

Loewenfeld,  R '03,    Uber   die  Geniale  Geistesthdtigkeit 

Meumann,  E '07,    Vorlesungen  zur  Einfilhrung  in  die 

Experimentelle  Pddagogik  und  ihre 
psychologischen  Grundlagen. 

Norsworthy,  N '06,  The  Psychology  of  Mentally  De- 
ficient Children,  Archives  of  Psy- 
chology, No.  I . 

Odin,  A '95,    Genbse  des  grands  hommes,  gens  de 

lettres  francais  modernes. 

Pearson,  K '04,    On  the  Laws  of  Inheritance  in  Man, 

II.  On  the  Inheritance  of  the  Men- 
tal and  Moral  Characters  in  Man, 
etc.,  Biometrika,  vol.  3,  Part  II, 
pp.  131-190. 


234 


Educational  Psychology 


Pearson,  K '07 ,    On  the  Relationship  of  Intelligence 

to  Size  and  Shape  of  Head,  and  to 
Other  Physical  and  Mental  Char- 
acters, Biometrika,  vol.  5,  pp.  105- 
146. 

Pedersen,  R.  H '05,    Experimentelle  Untersuchungen  der 

visuellen  und  akustischen  Erin- 
nerungsbilder,  angestellt  an  Schul- 
kindern,  Archiv  fur  die  gesamte 
Psychologie,  vol.  4,  pp.  520-534. 

Rice,  J.  M '97,    The  Futility  of  the  Spelling  Grind, 

The  Forum,  vol.  23,  pp.  163-172 
and  409-419. 
'02,    Educational  Research:    A    Test  in 
Arithmetic,   The   Forum,    vol.    34, 
pp.    281-297;     Causes    of  Success 
and    Failure    in    Arithmetic,    The 
Forum,  vol.  34,  pp.  437-452. 
'03,    Educational  Research,  The  Results 
of  a  Test  in  Language,  The  Forum, 
vol.  35,  pp.  269-293. 
'04,    English,  The  Need  of  a  New  Basis 
in  Education,      The   Forum,    vol. 
35,  pp.  440-457- 

Richardson,  H '02,    The   Etiology   of  Arrested   Mental 

Development,  Journal  of  Psycho- 
Asthenics,  vol.  7,  pp.  9-14. 

Segal,  J '08,    Uber  den  Reproduktionstypus  und 

das  Re  produzieren  von  Vorstel- 
lungen,  Archiv  fur  die  gesamte 
Psychologie,  vol.  12,  pp.  124-235. 

Simon,  Th '09,    (See  Binet  and  Simon.) 

Spearman,  C '04  (a),    The    Proof   and    Measurement    of 

Association  between  Two  Things, 
American  Journal  of  Psychology, 
vol.  15,  pp.  72-101. 
'04  (b),  "General  Intelligence"  Objectively 
Determined  and  Measured,  Amer- 
ican Journal  of  Psychology,  vol. 
15,  pp.  201-292. 

"  (with  F.  Krueger),    '06,    Die  Korrelaiion  zwischen  verschie- 

denen  geistigen  Leistungsfdhigkeit- 
en,  Zeitschrift  fiir  Psychologie,  vol. 
44,  pp.  50-114. 

Stern,  L.  W '00,    Uber  Psychologie  der  individuellen 

Differenzen. 


Authors  and  Titles  235 

Stone,  C.  W '08,    Arithmetical    Abilities    and    Some 

Factors  Determining  Them,  Colum- 
bia University  Contributions  to 
Education,  Teachers  College  Series, 
No.  19. 

Thompson,  H.  B '03,    Psychological  Norms  in  Men  and 

Women,  University  of  Chicago 
Contributions  to  Philosophy,  vol. 

4,  No.  I. 

Thorndike,  E.  L '03,    Heredity,  Correlation  and  Sex  Dif- 
ferences in  School  Abilities,  Colum- 
bia   University   Contributions    to 
Phil.,  Psy.,  and  Ed.,  vol.  11,  No.  2. 
'04,    An  Introductioti  to  the   Theory  of 
Mental  and  Social  Measurements. 
'05,    Measurements  of  Twins,  Archives 
of    Philosophy,    Psychology,    and 
Scientific  Methods,  No.  i. 
'08,    Memory    for     Paired     Associates, 
Psychological     Review,     vol.     15, 
pp.   122-138. 
'09,    The  Relation  of  Accuracy  in  Sen- 
sory Discrimination  to  General  In- 
telligence,    American    Journal    of 
Psychology,  vol.  20,  pp.  364-369. 
10,    Handwriting,      Teachers      College 
Record,  vol.  11,  No.  2. 

Ward,  L.  F '06,    Applied  Sociology. 

Wiersma,  E (See  Heymans  and  Wiersma.) 

Wissler,  C '01,    The    Correlatioti    of    Mental    and 

Physical  Tests,  Psychological  Re- 
view Monograph  Supplement  No. 
16,  June,  1901. 
'03,    The    Growth    of   Boys,    American 
Anthropologist,   New   Series,    vol. 

5,  pp.  81-88. 

Woods,  F.  A '06,    Mental    and    Moral    Heredity    in 

Royalty. 

Woodworth,  R.  S '10,    Racial  Differences  in  Mental  Traits, 

Science,  New  Series,  vol.  31,  pp. 
171-186. 

Wylie,  A.  R.  T '00,    Taste   and   Reaction    Time   of  the 

Feeble-Minded,  Journal  of  Psycho- 
Asthenics,  vol.  4,  No.  3;  A  Study 
of  tlie  Senses  of  the  Feeble-Minded, 
ibid.,  vol.  4,  No.  4;  Aleniory  of  the 
Feeble-Minded,  ibid.,  vol  5,  No.  i; 
Motor  Ability  and  Control  of  the 
Feeble-Minded,  ibid.,  vol.  5,  No.  2. 


APPENDIX    II 

List  and  Descriptions  of  Measurements  Referred  to  Cursorily  in  the 

Text 

A  Test:   Marking  A 's. 

A  sheet  printed  with  capital  letters,  as  shown  below,  is  used.  The 
individual  who  is  being  measured  is  instructed  'to  mark  as  many  A's 
as  he  can,'  or  'to  mark  as  many  and  omit  as  few  A's  as  he  can,'  or 
'to  mark  all  the  A's.'  The  score  used  is  the  number  marked  in  a  given 
time  (or  the  time  required  for  the  entire  sheet  to  be  gone  over)  and 
the  number  of  omissions. 

OYKFIUDBHTAGDAACDIXAMRPAGQZTAACVAOWLYX 

WABBTHJJANEEFAAMEAACBSVSKALLPHANRNPKAZF 

YRQAQEAXJUDFOIMWZSAUCGVAOABMAYDYAAZJDAL 

JACINEVBGAOFHARPVEJCTQZAPJLEIQWNAHRBUIAS 

SNZMWAAAWHACAXHXQAXTDPUTYGSKGRKVLGKIM 

FUOFAAKYFGTMBLYZIJAAVAUAACXDTVDACJSIUFMO 

TXWAMQEAKHAOPXZWCAIRBRZNSOQAQLMDGUSGB 

AKNAAPLPAAAHYOAEKLNVFARJAEHNPWIBAYAQRK 

UPDSHAAQGGHTAMZAQGMTPNURQNXIJEOWYCREJD 

UOLJCCAKSZAUAFERFAWAFZAWXBAAAVHAMBATAD 

KVSTVNAPLILAOXYSJUOVYIVPAAPSDNLKRQAAOJLE 

GAAOYEMPAZNTIBXGAIMRUSAWZAZWXAMXBDXAJZ 

ECNABAHGDVSVFTCLAYKUKCWAFRWHTQYAFAAAOH 

a — t  Test:   Marking  Words  Containing,  Each,  Both  a  and  t. 

A  sheet  printed  with  text,  as  shown  below,  is  used.  The  individual  who 
is  being  measured  is  instructed,  and  the  score  is  kept,  as  in  the  A  test. 
The  same  sheet  is  used  for  marking  words  containing  other  combina- 
tions of  letters,  such  as  r  and  e,  or  i  and  /. 

A. 

Dire  tengo  antipatia  senores;  esto  seria  necedad,  porque  hombre  vale 
siempre  tanto  como  otro  hombre.  Todas  clases  hombres  merito; 
resumidas  cuentas,  sulpa  suya  vizconde;  pero  dire  sobrina  puede 
contar  dote  veinte  cinco  duros  menos,  tengo  apartado ;  pardiez  tamado 

(236) 


Descriptions  of  Measurements  237 

trabajo  atesorar-los  para  enriquecer  estrano.  Vizconde  rico.  Mios, 
quiero  ganado  sudor  frente  saiga  familia;  suyo,  pertenence,  tendran. 
Conozco  marido  pueda  convenirle  Isabel:  Carlos,  sobrino.  Donde 
muchacho  honrado,  mejor  indole,  juicioso,  valiente?  Quieres  sobrino. 
Esposo  parece  natural,  pero.  Pero,  pero,  diablos  objeciones  hacer. 
Posible  quedandonow  solos  siempre  hacer  oposicion.  Solo  delante 
hentes  eres  ministerial.  Pues,  sidens  siempre  plan,  dicho  antes,  porque 
hace  tiempo  notade  cose  aflige  cierto.  Sabes  cuante  quiero  Carlos; 
consuelo  apoyo;  despues  persona  quiero  mundo.  Como  eres  buena 
amable,  quieres  porque,  darme  gusto,  pero  quisiera.  Palabra  cuesta 
trabajo;  parece  sino  teines  miedo  agasajarle,  manifestarle  carino. 
Veces  tratas  cumplimiento  veces  senor.  Probare ;  ejemplo  pudiendo 
abandonar  case  negocios,  deseaba  hubiese  acompanado  viaje;  pre- 
feriste  sola  sobrina  doncella.  Quise  contradecir,  pero  para  sen- 
timiento,  para  tambien.  Voto  gasta  palabra,  dice  frases,  dice;  pero 
alia  adentros  quiere.  Mientras  estado  malo,  puesto  dirigir  casa; 
pardiez  aunque  carrera,  hacia  mejor;  cabo  tiene  sobre  ventaja  poca 
edad,  actividad  zelo,  pues  para  contigo  digo.  Siempre  ordenes;  dejaria 
matar  alcanzarte  billete  para  opera  para  baile.  Necsitamos  para  felices; 
algo  estrano,  desconocido.  Esta  resuelto;  supuesto  hemos  hablado 
esto,  mismo  preciso  empieces  dark  conocer  nuestros  planes.  Quien 
mejor.  Opone  nunca  deseos,  sera  facil  nadie  persuadirle.  Probare 
menos,  preciso  sino  creere  tienes  interes  decidido  proteger  vizconde. 
Pudieras  creer  siempre  inclinado  senores  cabra  tira  monte.  Pero  tengo 
nada  ellos  esposo  tienes  siempre  pensativo  siempre  trists.  Diablos 
tiene  Carlos  acercate,  tiene  hablarte.  Hola  parece  sacado  letargo  tengo 
algunas  instrucciones  cajero  marcha  dentro  poco.  Para  empresa  piesna 
usted  establecer  Habana.  Precisamente  bonita  especulacion  bien 
manejada  sobro  todo.  Espero  pero  tengo  entre  manos  etro  proyecto 
interesa  aqui  estabamos  ocupando  pienso.  Eres  porque  quieres 
B. 
porque  e  tregas  defensa  peligro  lugar  huir  mujer,  harto  debil  duda  pero 
algun  desgracia  tuviese  luchar  sentimientos  semejantes  tuyos,  lejos 
ceder  ellos  cobardemente  moriria  pero  triunfaria.  Tendras  menos 
valor  tendre  darte  lecciones  valor  energia.  Vamos,  Carlos,  amigo 
creeme  sentimiento,  profundo  razon  pueda  subyugar,  desgracia  grande 
pueda  soportar  veneer  nuestro  corazon.  Ofrezco  apoyo  eres  creo  sequiras 
consejos.  Bien,  hable  usted.  Quiere  casarte  Isabel.  Isabel,  prima 
imposible;  quiere  otro,  vizconde  amigo.  Preciso  persuadirselo  hare 
otros  partidos  habra  jamas  para  jurado  nada  espero  pero  conservare 
siempre  entero  este  amor  ella  ignora  unos  juramentos  recibido.  En- 
horabuena  otro  medio  asequarara  tranquilidad,  uya  destino  ofrecido 
aleja  Madrid,  preciso  aceptarle.  Privarme  presencia  felicidad  hecho 
usted  para  consejo  especie  embargo  preciso  seguirle  solo  puedes  con- 
servar  amistad  elige.  Jamas  caballero  crei  usted  digno  consejos  dejo 
usted  abandonado  mismo  nada  tango  decirle  Carlos  aleja,  echa  mirade 
salir  Dona  mira;  suspira  sale.  Porque  inquieta  partida  desterremos 
para  siempre  memoria  quiero  puedo  presente  temo;    ausente,  echo 


238  Educational  Psychology 

menos,  verle  sonrojo,  nombre  hace  temblar.  Embargo  nunca  dicho 
debiera  ignorarlo  Dios  Dame  fuerzas  para  resistir. 

Alphabet  Test. 

A  sheet  printed  with/,  k,  s,  p,  u,  I,  e,  r,  d,  0,  v,  j,  n,  t  and  fe  in  a  column 
is  used.  Instructions  are: — 'to  write  after  each  letter,  the  letter  that 
comes  immediately  before  it  in  the  alphabet.'  The  score  records 
time  required  (or  number  written  in  a  given  time),  errors  and  omissions. 

Genus-Species  Test. 

A  sheet  printed  with  book,  tree,  room,  toy,  name,  dish,  boat,  game,  plant 
andjish  in  a  column  is  used.  Instructions  are: — 'to  write,  after  each 
word,  a  word  which  means  some  kind  of  the  thing  named  by  the  printed 
word.'  The  score  is  kept  as  in  the  Alphabet  test.  The  words  may 
be  given  to  the  subject,  and  the  replies  made  by  him  orally.  A  harder 
list  is  used  for  older  children. 

Geometrical  Forms  Test:  Marking  Circles,  Hexagons,  etc. 

A  sheet  printed  with  Fig.  71  is  used.  Instructions  and  scoring  are  as 
in  the  A  or  a — t  test. 

Ma2e  Tests.     Drawing  a  Line  between  Two  Given  Lines. 

Sheets  printed  with  Fig.  72,  or  similar  mazes,  are  used.  The  instructions 
are  to  draw  a  line  along  the  pathway  as  quickly  as  possible  without 
touching  the  sides.  The  score  includes  amount  done  (or  time  taken), 
and  number  of  touches. 

Memory  of  Related  Words. 

Memory  of  such  series  as: — school,  teacher,  book,  desk,  pen,  read,  write, 
add,  spell,  word. 

Memory  of  Unrelated  Words. 

Memory  of  such  series  as: — red,  dog,  buy,  day,  ncTer,  sing,  boy,  sick,  tree, 
can. 

Misspelled  Word  Test:   Marking  Misspelled  Words. 

Sheets  printed  with  passages  like  that  below  are  used.  Instructions  and 
scoring  are  as  in  the  A  test. 

1.  On  the  3d  of  September,  1832,  inteligence  was  broght  to  the  collecter 
of  Tinnevelly  that  som  wildd  eliphants  had  appeared  in  the  neighbor^ 
hod.  A  hunting  party  was  imediately  formed,  and  a  large  number  of 
nattive  hunters  were  engaged.  We  left  the  tents,  on  horsback,  at 
half-past  sevin  o'clock  in  the  morrning  and  rode  thre  miles  to  an  open 
spote,  flanked  on  one  sid  bye  Rice-fields,  and  on  the  other  by  a  jungle. 

2.  After  waiting  som  time,  Captain  B and  myself  walked  acros  the 

rice-fields  to  the  shad  of  a  tree.  There  we  herd  the  trumpett  of  an 
elephant;  we  re.shed  acros  the  rice-fields  up  to  our  knes  in  mud,  but 
all  in  vaiu,  thogh  we  came  upon  the  trak  of  one  of  the  animels,  and 
then  ran  five  or  six  hundredd  yards  iutoo  the  jungle. 


I 


Descriptions  of  Measurements 


239 


o 


^2^ 


o 


00<]^DoAo9 


An 


<vgAOP;:^ 

c 

O 


nn^SoA 


5bSL:-thR . 

Lj[f  D  O 


D 


<d 


o 


^orqU  on 


D 

r 


hfeLl 


;> 


D^C^ 


coLDnoc:^n<i 
^'OcudDPd  n<aono 


240 


Educational  Psychology 


Descriptions  of  Measurements  241 

3.  After  varius  false  allarms,  aud  vane  endevors  to  discuvor  the  obgects 

of  our  chace,  the  colector  went  into  the  jungle,  and  Captin  B 

and  myself  into  bed  of  the  stream'  where  we  had  sen  the  traks;  and 
here  it  was  evedent  the  elaphents  had  passed  to  and  fro.  Disapointed 
and  impasient,  we  allmost  determined  to  giv  up  the  chace  and  go 
home;  but  shots  fird  just  before  us  reanimated  us,  aud  we  proceded, 
and  found  the  collecter  had  just  firred  twicce. 

4.  Of  we  went  throuh  foerst,  over  ravin,  and  through  strems,  till  att 
last,  at  the  top  of  the  ravine,  the  elephants  were  seen.  This  was  a 
momant    of   excitment!     We    wer    all    scatered.     The    collector    had 

taken  the  midle  path;    Captain  B ,  some  huntsmen,  and  myself 

took  to  the  feft;  and  the  other  hunters  scrabled  down  that  to  the 
rite.  At  this  momunt  I  did  not  see  enything  but  after  advanceing  a 
few  yards,  the  hugh  hed  ef  an  elephunt  shaking  abuve  the  jungle, 
withen  ten  yards  of  us,  burst  sudenly  upon  my  view. 

5.  Captain  B ande  a  hunter  justt  befor  me:    we  al  fired  at  the 

same  moment,  and  in  so  dirrect  a  line  thet  the  percussion  cap  of  my 
gun  hitt  the  hunter,  whome  I  thougt  at  first  I  had  shoot.  This  accident, 
thogh  it  pruved  slight,  troubled  me  a  litle.  The  grate  excitement 
ocasioned  by  seeing,  for  the  first  tim,  a  wild  best  at  liberty  and  in  a 
state  of  natur,  product  a  sensation  of  hop  and  fear  that  was  intens. 

Opposite s  Tests. 

Sheets  printed  with  words  in  a  column  are  used,  one  list  being: — good, 
outside,  quick,  tall,  big,  loud,  white,  light,  happy,  false,  like,  rich,  sick, 
glad,  thin,  empty,  war,  many,  above  and  friend.  Another  list  is: — bad, 
inside,  slow,  short,  little,  soft,  black,  dark,  sod,  true,  dislike,  poor,  well 
sorry,  thick,  full,  peace,  few,  below  and  enemy. 

Harder  lists,  used  for  older  children  and  adults,  are: — serious,  grand, 
clumsy,  to  win,  to  respect,  frequently,  apart,  stormy,  motion,  forcible, 
to  float,  straight,  to  hold,  after,  unless,  rough,  to  bless,  to  take;  and  bar- 
barous, simple,  rude,  obscure,  gentle,  to  expand,  elation,  adroit,  loquacious, 
to  degrade,  to  hinder,  precise,  permanent,  repulsion,  to  respect,  genuine, 
separate,  deceitful. 

Instructions  are  to  write  (or,  if  the  test  is  given  orally,  to  say)  the  word 
which  means  the  opposite  of  the  given  word,  'just  what  that  word 
does  not  mean.'     The  score  is  kept  as  in  the  Alphabet  test. 

Part-Whole  Test. 

To  give  the  name  of  that  whole  thing  of  which  the  printed  or  spoken 
word  is  a  part.  The  list  used  for  young  children  and  for  mentally 
deficient  individuals  is: — door,  pillow,  letter,  leaf,  button,  nose,  corer 
page,  engine,  and  glass. 

Word  Test. 

To  write  words  conforming  to  certain  requirements,  such  as: — 'to  contain 
six  letters,'  or  'to  contain  a  and  g.' 
16 


APPENDIX  III 
List  and  Definitions  of  Statistical  Terms 

Measures  of  Central  Tendency. 

The  Average  =  (the  sum  of  the  individual  measures)  -r-  (their  number). 
The   Median  —  the   middle   measure,   the   measure   so   chosen   that   the 

number  of  measures  greater  than  it  equals  the  number  less  than  it. 
The  Mode  =  the  most  frequent  of  the  individual  measures. 
Measures  of  Variability. 

The  Average  Deviation  (A.   D.  dis.)  =  the  average  of  the  deviations 

(regardless  of  signs)   of  the  individual  measures  from  their  central 

tendency. 
The  Median  Deviation  (P.  E.  dis.)  or  Probable  Error  (when  used  as  a 

measure  of  variability)  =  the   median  of   the   deviations   (regardless 

of  signs)  of  the  individual  measures  from  their  central  tendency. 
The  Mean  Square  Deviation  (S.  D.  dis.)  =    the  square  root  of  the  average 

of  the  squares  of  the  deviations  of  the  individual  measures  from  their 

central  tendency. 

Measures  of  Reliability. 

The  average  deviation  of  the  true  central  tendency  from  that  obtained 

A  D    dis 
from  a  random  selection  of  n  measures  ( A.  D.  ^^j. ^^  ^  t  )~   ~ — " 

•    ■    ■  l/n 

Similarly, 

T^  P  E  dis  S.  D.  dis. 

P-^-  tr.-ob.C.T.=      '^—       ^""^    ^•^•tr.-ob.C.T.=  ~J7^=" 

For  measures  of  the  reliability  of  measures  of  variability  and  of  relations 
see  Thorndike,  Mental  and  Social  Measurements,  Chapter  X. 
Measures  of  Relations. 

Let  xi,  X2,  X3,  X4,  etc.,  be  the  first  series  of  divergences. 

Let  yi,  y2,  ys,  yt,    "     "     "    second  "     "  " 

Let  ^  x.y  be  the  sum  of  the  products  xiyi,    X2y2,   xsys,   X4y4,  etc. 

Let  2  x^      "     "       "       "     "   squares  xi^,  x^,  xg^,  Xi^,  etc. 

Let  2"  y^    "    "      "     "    "       "      yi^,  y2^,  ys^,  y4^,  etc. 

I  x.y 

Then  the  Pearson  Coefficient  of  Correlation,  R,  = 

l/j  x2  .  J  y2 

For  other  measures  of  relations  see  the  author's  Mental  and  Social 
Measurements,  Chapter  IX,  and  Empirical  Studies  in  tlie  Theory  of 
Measurement,  §§  5  to  9,  inclusive. 
(242) 


INDEX  OF  NAMES 


Barr,  M.  W.,  102. 
Betts,   G.    H.,    183,    195. 
Binet,  A.,  203,  215. 
Brown,  W.,  182. 
Bruner,  F.  G.,  56,  57. 
Burris,  W.  P.,  96. 
Burt,  C,   181,  182,  184. 

Cattell,  J.  McK.,  35  f.,  119,  121  ff.,  184. 
Cole,  L.  W.,  40. 
Cornman,  O.  P.,  78,  135. 
Courtis,   S.   A.,   135. 

Davenport,  C.  B.,  102. 
DeCandolle,  A.,  121. 


Earle,  E.  L.,  40,  T7  f. 
Ellis,  H.,  zd,  49  f-,  61  flf.,  94  U 
225  flf. 

Fay,  E.  A.,  "jy. 
Fox,  W.  A.,  40. 

Galton,  F.,  65   f.,  70,   78,   79,  93. 

119  ff.,   121,  215. 
Gilbert,  J.  A.,  30  f.,  40,  105  ff , 

Heymans,  G.,  45,  46,  48,  92,  93 

Jacobs,  J.,  215. 
Jacoby,   P.,   121. 
Johnson,  G.  E.,  215. 

Kelly,  R.  L.,  215. 
Kraepelin,  E.,  204. 
Kuhlmann,   F.,  215. 

Learoyd,  M.  W.,  50. 
Leclere,  A.,  203. 
Lobsien,  M.,  215. 
Loewenfeld,  R.,  79,  227. 


121, 


94, 


113- 


McDougall,   W.,   56,   57. 
Mayo,  M.  J.,  52  ff. 
Mendel,  G.,  98. 
Meumann,  E.,  183,  194,  201. 

Norsworthy,    N ,  215,  217,   221. 

Odin,    A.,    121. 

Pearson,  K.,  43  f.,  80,  81,  82,  83,  84, 

96,   182,  224. 
Pedersen,  R.  H.,  183. 

Ranke,  J.,  55. 

Rice,  J.  M.,  78,  119,  125  ff. 
Richardson,  H.,  103. 
Rivers,   W.    H.   R.,   56,   59- 

Segal,  J.,  194. 

Seguin,  E.,  218. 

Simon,  Th.,  215. 

Simpson,  B.  R.,  182. 

Sollier,  P.,  219. 

Spearman,  C,  80,  182,  185,  188. 

Stern,  L.  W.,  201  ff. 

Stone,  C   W.,   I35- 

Strayer,  G.  D.,  42. 

Thompson,   H.  B.,  20  ff.,  12,  37,  42. 
Thorndike,    E.    L.,   89,   96,    I35,    165, 
182,  184. 

Ward,  L.  F.,  121. 
Wiersma,  E.,  45,  46,  48,  92,  93. 
Wissler,  C,  30,  43,  182,  188. 
Woods,  F.  A.,  84  ff.,  124,  224. 
Woodworth,  R.  S.,  55  ff- 
Wylie,  A.  R.  T.,  215. 


(243) 


INDEX   OF  SUBJECTS 


Ability,  inheritance  of,  80  ff. 

Abnormal.      See    Exceptional. 

Achievement,  relative  versus  absolute, 
138  ff. 

Activities,  sex  differences  in,  46  ff. 

Addition,  individual  differences  in, 
144  f. 

Age,  changes  in  mental  traits  with, 
105  ff. 

Ancestry.    See  Inheritance. 

Arithmetic,  differences  of  school 
classes  in,  129;  the  causes  of  ability 
in,    129,    131    ff. 

Arrested  development,  228  ff. 

Artistic  faculty,  inheritance  of,  80. 

Assertiveness,  inheritance  of,  80  ff. ; 
sex  differences  in,  44  f. 

Association,  sex  differences  in,  30  f. ; 
the  inferiority  of  intellectually  defi- 
cient individuals  in,  218;  the  in- 
heritance of  speed  and  control  in, 
89  ff. 

Athleticism,  inheritance  of,  83 ;  sex 
differences  in,  44  f. 

Attenuation  of  resemblances,  80  f. 

Average  Deviation,  13  f.  See  also 
Measurement. 

Averages.     See  Measurement. 

Brightness.     See  Senses. 
British   genius,   racial   differences   in, 
61  ff. 

Central  Tendency,  12. 
Cephalic  index,  inheritance  of,  72,  76. 
Chance   form   of   distribution,    160   ff. 
Character,  sex  differences  in,  44  ff. ; 
types   of,   193  ff. 


Characters,   unit   and  multiple,  98  ff. 

Classification,  of  individuals,  142-206 
passim;  of  individuals  exceptionally 
inferior  in  intellect,  213  f. ;  of  in- 
dividuals exceptionally  inferior  in 
morals,  223   f. 

Color.    See  Senses. 

Combinations  of  traits,  3  f.,  193  ff. 

Compensations  in  mental  relations, 
183  ff. 

Conscientiousness,  inheritance  of, 
80  ff. ;  sex  differences  in,  44  f. 

Continuity  of  variations,  149  f. 

Correlations      See  Relations. 

Curve  of  frequency,  16.  See  also  Dis- 
tribution   and    Distributions. 

Dealing,  relations  of  ability  in,  181  f. 
Defectives.     See  Exceptional. 
Determiners    of   traits    in   the    adult, 

97  ff. 

Deviations.  See  Individual  Differ- 
ences, Distributions,  Distribution  of 
Amounts  of  a  Trait,  and  Varia- 
bility. 

Dilation  of  resemblances  by  variations 
in  the  scales  used,  81  f.,  83. 

Discrimination.  See  Sensory  Dis- 
crimination and  Senses. 

Distribution  of  amounts  of  mental 
traits,  15  f.,  142  ff. ;  as  affected  by 
mixture  of  species,  166;  as  affected 
by  selection,  167  ff. ;  as  affected  by 
the  number  of  cases,  159;  multi- 
modality  of,  152  ff. ;  the  probability 
type  of,  160  ff.  See  also  Individual 
Differences   and   Variability. 

Distributions,  corresponding  to  stated 


(244) 


Index  of  Subjects 


245 


group  differences,  28  f.,  33,  64, 
66;  of  adult  women,  in  add- 
ing, 144  f.,  150,  in  discrimination  of 
length,  144,  in  memory  of  digits, 
151 ;  of  boys,  in  giving  opposites, 
151,  in  marking  A's,  151,  in  mark- 
ing words  containing  a  and  t,  151; 
of  boys  and  girls,  in  age  at  reach- 
ing a  given  grade,  42,  158,  in  mark- 
ing A'Sj  154  f. ;  of  individuals,  in 
combinations  of  traits,  194  ff. ;  of 
men,  in  reaction-time,  151 ;  of  men 
and  women,  in  ingenuity,  23,  25 ;  of 
relationships,  174  ff. ;  of  whites  and 
Negritos,  in  the  block  test,  61,  156; 
of  whites  and  negroes,  in  scholar- 
ship, 54  f.,  157. 

Economics,  sex  differences  in  scholar- 
ship in,  31. 

Emotions,  sex  differences  in,  44  ff. 

English,  sex  differences  in  scholar- 
ship in,  31. 

Environment,  and  maturity,  the  co- 
operation of,  109  f. ;  and  original 
nature,  the  cooperation  of,  138  ff.  ; 
as  a  cause  of  multimodality  or  dis- 
tinct types,  153  f.,  154  f. ;  as  a  cause 
of  sex  differences,  38,  42;  differ- 
ences in  as  causes  of  individual 
differences  in  ability  in  arithmetic, 
129,  131  ff.,  in  ability  in  spelling, 
126  ff.,  in  scientific  achievement, 
122  f.,  in  the  choice  of  a  profession, 
134  f. ;  is,  in  part,  selected  by  an 
individual's  nature,  117;  resem- 
blances in,  as  causes  of  individual 
resemblances  in  ability  to  learn  to 
spell,  78,  in  genius,  79,  in  various 
mental  traits,  83-93  passim;  the 
action  of  is  differential,  116  f . ;  the 
influence  of  in  the  case  of  twin?, 
119  ff. 

Exceptional  inferiority,  21  r  ff. ;  in 
intellect,  213  ff. ;   in  morals,  223   f. 

Exceptionally  defective  individuals 
intellectually,  213   ff. ;   classification 


of,  213  f. ;  general  description  of, 
219  f. ;  measurements  of,  215  ff., 
221  f. ;  relative  inferiority  of  in  dif- 
ferent traits,  216  f. ;  symptoms  of, 
214;  treatment  of,  214  f. 

Exceptional  rates  of  growth,  224  ff.  ; 
rapid  growth,  225  ff. ;  slow  growth, 
228  f. 

Exceptional  superiority,  209  f. 

Extreme  individual  differences,  207  ff. 

Eye-color,  inheritance  of,   76. 

Fallacy  of  unfair  selection,  112,  ii4f. 

Family.     See  Inheritance. 

Fatigue,  age  differences  in,  105  ff. ; 
sex  differences  in,  27. 

Feeble-mindedness.  See  Exception- 
ally Defective  Individuals. 

Frequency.  See  Distribution,  Dis- 
tributions, and  Variability. 

Genius,  inheritance  of,  78  f. ;  racial 
differences  in,  61  ff. ;  sex  differ- 
ences in,  35  f. 

Groups,  measurement  of  differences 
between,  24  ff.,  2)7  ff- 

Growth.     See   Maturity. 

Habits,  effect  of  on  relations,  191  f. ; 
formation  of  in  individuals  excep- 
tionally defective  in  intellect,  214  f. ; 
indifference  of  certain  habits  to  all 
natures,  137  f. ;  not  measures  of 
capacity,  67  ;  relation  to  multimodal- 
ity, 153  f. ;  susceptibility  of  to 
environmental  influence,  141. 

Hair-color,  inheritance  of,  yy. 

Handwriting,  inheritance  of,  80  ff. ; 
sex  differences  in,  44  f. 

Heredity.      See    Inheritance. 

History,  sex  differences  in  scholar- 
ship in,  31. 

Idiocy.     See  Exceptionally  Defective 

Individuals. 
Illusions,  sex  differences  in,  30  f. 


246 


Educational  Psychology 


Imagery,  individual  dififerences  in, 
193  ff. 

Imbecility,  and  Mendelian  inherit- 
ance, 102  f.  See  also  Exceptionally 
Defective   Individuals. 

Immaturity,  tests  of,  229. 

Individual  differences,  environment  as 
a  cause  of,  114  ff. ;  extreme,  207  ff. ; 
immediate  ancestry  as  a  cause  of, 
69  ff. ;  in  combinations  of  traits, 
193  ff. ;  in  single  traits,  142  ff. ; 
maturity  as  a  cause  of,  104  ff. ; 
measurement  of,  3  ff. ;  remote 
ancestry  as  a  cause  of,  51  ff. ;  sex 
as  a  cause  of,   18  ff. 

Information,  sex  differences  in 
amount   of,   28. 

Ingenuity,  sex  differences  in,  28. 

Inheritance,  analysis  of,  97  ff. ;  and 
education,  138  ff. ; '  and  responsibil- 
ity, 140;  blended  versus  Mendelian, 
99  ff. ;  from  near  ancestry,  69  ff. ; 
from  remote- ancestry,  51  ff-;  Men- 
delian, 98  ff. ;  of  abihty,  80  ff. ;  of 
ability  to  learn  to  spell,  77  f. ;  of 
artistic  faculty,  80;  of  assertiveness, 
80  ff. ;  of  athletic  ability,  83;  of 
cephalic  index,  72,  76;  of  conscien- 
tiousness, 80  ff. ;  of  deafness,  77; 
of  eye-color,  76 ;  of  genius,  78  f. ; 
of  hair-color,  77;  of  handwriting, 
80  ff. ;  of  imbecility,  102  f. ;  of  in- 
tellect, 84  ff. ;  of  morals,  84  ff. ;  of 
popularity,  80  ff. ;  of  self-conscious- 
ness, 80  ff. ;  of  stature,  76 ;  of  tem- 
per, 80  ff. ;  of  vivacity,  80  ff. ; 
specialization  of,  93  ff. 
Instincts,  sex'  differences  in,  48  f. 
Intellect,  defects  of,  207  ff. ;  inherit- 
ance of,  78,  80  ff. ;  racial  differences 
in,  58  ff. ;  sex  differences  in,  44  ff. ; 
types  of,  193  ff. 
Interests,  sex  differences  in,  46  ff. 
Inverse  correlations,  200. 

Languages,  sex  differences  in  scholar- 
ship in,  31. 


Mathematics,     sex       differences       in 

scholarship  in,  31. 
Maturity,  and  environment,  the  co- 
operation of,  109  f. ;  exceptional 
individuals  in  the  rate  of,  224  ff. ; 
the  influence  of  upon  individual 
mental  differences,  104  ff. ;  the  in- 
fluence of  upon  multimodality,  155  ; 
the  measurement  of  the  influence 
of,   104,   iioff. 

Measurement,  of  changes  with  age, 
I  ID  ff. ;  of  group  differences  in 
amount,  24  ff. ;  of  group  differences 
in  variability,  37  ff. ;  of  individual 
differences,  3  ff. ;  of  mental  rela- 
tions, 172  ff. ;  of  relative  inferiority 
in  different  traits,  216  f. ;  of  resem- 
blance, 71  ff. ;  of  variability,  15  ff. 

Measurements.  See  the  references 
given  under  the  subject  concerned. 

Median,  13. 

Median  ratio,  74. 

Memory,  in  individuals  exceptionally 
deficient  in  intellect,  219,  221  f. ;  of 
digits,  distribution  of,  151;  relations 
of,  182;  sex  differences  in,  28,  30  f. 

Mental  science,  sex  differences  in 
scholarship  in,  31. 

Mode,  12. 

Moral  traits,  exceptional  inferiority  in, 
223  f. ;  inheritance  of,  80  ff.,  86  ff., 
92  f. ;  sex  differences  in,  44  ff. 

Motor  ability,  differences  in,  due  to 
age,  105  ff. ;  differences  in,  due  to 
sex,  27,  30  f. ;  in  individuals  excep- 
tionally deficient  in  intellect,  218  f., 
221  f. 

Multimodality,  152  ff. 

Multiple  type  theory,  152  ff.,  I95  ff- 


Negritos,  ability  of  in  matching 
forms,  60  f. 

Negroes,  and  whites  compared  in 
scholarship,  52  ff. ;  intellectual 
powers  of,  according  to  Galton,  O5  f. 

Nurture.     See  Environment. 


Index  of  Subjects 


247 


Objective  measurements,  5  f. 
Opposition  of  traits.     See  Relations, 
inverse. 

Pain.    See  Senses. 

Pearson  coefficient  of  correlation, 
74  ff.,  180  f. 

Perception,  distribution  of  individuals 
in,  151 ;  inheritance  of  ability  in, 
89  flf. ;  racial  differences  in,  58;  sex 
differences  in,  27,  30  f.,  41 ;  special- 
ized in  inheritance,  97  f. 

Pitch.     See   Senses. 

Popularity,  inheritance  of,  80  ff. ;  sex 
differences  in,  44  f. 

Precocity,  225  f. 

Pressure.     See  Senses. 

Primitive  races,  mental  traits  of  55  ff. 

Probability  form  of  distribution,  160  ff. 

Profession,  causes  of  an  individual's 
choice  of  a,  134  f. 

Qualitative  differences,  reducible  to 
quantitative,  4. 

Race,  as  a  cause  of  individual  differ- 
ences, 51  ff. ;  as  a  cause  of  multi- 
modality,  154  f. 

Races,  the  interpretation  of  the  dif- 
ferences of,  in  achievement,  64  ff. 

Range  of  sensitivity.     See  Senses. 

Rates  of  growth,  exceptional,  224  ff. 

Reaction  time,  age  differences  in, 
105  ff. ;  distribution  of  ability  in, 
151 ;  sex  differences  in,  27,  30  f. 

Relations  between  amounts  of  differ- 
ent traits  in  the  same  individual, 
171  ff. ;  common  factor  in,  185  f. ; 
comparison  of,  179  f . ;  curvilinear, 
178  f . ;  general  features  of,  189  ff . ; 
inverse,  183  ff.,  200;  measurement 
of,  172  ff. ;  rectilinear,  177  ff. ;  signi- 
ficance of,  183  ff. ;  through  identity 
of  form,  186  ff. ;  variability  of, 
174  ff.    See  also  Resemblances. 

Reliability  of  mental  measurements, 
II  ff. 


Resemblances,   attenuation   of,  80    f. ; 

dilation  of,  81  f.,  83 ;  measurement 

of,  71    ff. 
Royal  families,  hereditary  resemblance 

in,  84  ff. 

Scales,  for  mental  traits,  5  ff. 
Scholarship,    of   whites   and    negroes 
compared,  52  ff.,  sex  differences  in, 

31- 

School  progress,  sex  difference  in 
variability  in,  41  f. 

School,  work,  individuals  failing  in, 
220  f. 

Science,  the  causes  of  achievement  in, 
122  ff. 

Selection,  fallacies  due  to  unfair,  112, 
114  f . ;  influence  of  on  the  form  of 
distribution,   167   ff. 

Selective  thinking,  inferiority  of  in- 
tellectually deficient  individuals  in, 
218,  222  f. ;  sex  differences  in,  31. 

Self-consciousness,  inheritance  of, 
80  ff. ;  sex  differences  in,  44  f. 

Senses,  age  differences  in  the,  105  ff. ; 
racial  differences  in  the,  55  ft". ;  sex 
di-fferences  in  the,  27  ff. 

Sensory  discrimination,  individual  dif- 
ferences in,  144  f.,  151  ;  inferiority 
of  intellectually  deficient  individuals 
in,  218  f. ;  relations  of,  181  f.  See 
also  Senses. 

Sex,  as  a  cause  of  individual  differ- 
ences, 18  ff. ;  as  a  cause  of  multi- 
modality,  154. 

Sex  differences,  18  ff. ;  in  abilities, 
20  ff. ;  in  character  and  interests, 
43  ff. ;  in  variability,  34  ff. 

Sexes,  differences  in  the  training  of 
the,  18,  32. 

Sh>Tiess,  sex  differences  in,  44  f. ; 
the  inheritance  of,  80  ff. 

Simple  and  compound  differences,  3  f. 

Single  tj'pe  theory,  145,  168  ff.,  195  ff. 

Skewness  of  distribution,  167  ff. 

Slow  growth,  228  ff. 

Sorting,  relations  of  abilities  in,  181  f. ; 
sex  differences  in,  27. 


248 


Educational  Psychology 


Specialization,  of  heredity,  93  ff. ;  of 
mental   traits,    186   ff. 

Speed  of  mental  and  motor  processes, 
racial  differences  in,  58. 

Spelling,  differences  of  different 
school  classes  in,  127  f. ;  sex  differ- 
ences in,  31 ;  the  causes  of  ability 
in,  126  ff. ;  the  inheritance  of  the 
ability  to  learn,   77  f. 

Stature,  inheritance  of,  76;  of  mental 
defectives,  218. 

Subjectivity,  of  measures,  5  ff. ;  sex 
differences  in,  50. 

Suggestibility,  differences  in  due  to 
age,  105  ff. 

Surface  of  frequency.  See  Distribu- 
tion. 

Tapping,  relations  of  ability  in,  181  f. ; 
sex   differences   in,   27. 

Taste.     See   Senses. 

Temper,  inheritance  of,  80  ff. ;  sex 
differences  in,  44  f. 

Temperament,  individual  differences 
in,  195 ;  sex  differences  in,  44  ff. 

Temperature,  of  individuals  exception- 
ally inferior  in  intellect,  221  f.  See 
also   Senses. 

Tests.  See  the  references  under  the 
subjects  concerned.  See  also 
Appendix  II. 

Threshold.    See  Senses. 


Touch.    See  Senses. 

Training.    See  Environment. 

Twins,  resemblances  of,  72  ff.,  89  ff. ; 
specialization  of  inheritance  in, 
96  ff. ;  the  action  of  likenesses  and 
differences  in  the  environment  upon, 
119  ff. 

Types  of  intellect  and  character, 
171   ff.,  193  ff. 

Variability,  allowance  for  in  the  com- 
parison of  defects  in  different  traits, 
266  f. ;  allowances  for  in  the  com- 
parison of  relations,  178  ff. ;  compari- 
son of  groups  in  respect  to,  37  ff. ; 
methods  of  measuring,  15  ff. ;  of 
determiners,  loi ;  of  different 
measures  of  ostensibly  the  same 
mental  fact,  11  ff. ;  of  germs  from 
the  same  parents,  71 ;  of  individuals 
^^  the  same  sex  and  ancestry,  69  ff. ; 
of  races,  53 ;  of  the  same  groups  in 
different  traits,  144  ff. ;  of  the  sexes, 
33  ff. ;  reduction  of  in  individuals  of 
similar  ancestry,  72.  See  also 
Individual  Differences  and  Distribu- 
tion. 

Vivacity,  inheritance  of,  80  ff. ;  sex 
differences  in,  44  f. 

Weight,  of  mental  defectives,  218. 
Zero-points  for  mental  scales,  146  ff. 


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